Infertility and Diseases in Animals PDF

Infertility A number of disease conditions cause infertility in the sow. Brucella suis or brucellosis is spread by breeding and causes embryonic death, abortion, and infertility, as well as orchitis in the boar. Porcine parvovirus causes infertility, mummi ication, and stillbirth in naı̈ve herds. Af...

Infertility A number of disease conditions cause infertility in the sow. Brucella suis or brucellosis is spread by breeding and causes embryonic death, abortion, and infertility, as well as orchitis in the boar. Porcine parvovirus causes infertility, mummi ication, and stillbirth in naı̈ve herds. After herd infection, immunity to porcine parvovirus generally develops. Hog cholera causes a number of problems in the pregnant sow, including embryonic death, abortion, mummi ication, stillbirths, decreased litter size, and weak piglets. Pseudorabies in a pregnant sow causes abortion 10 to 20 days after signs of illness. Leptospirosis pomona causes abortions during the last month of pregnancy, although the sow may appear normal. The smedi virus causes many problems, such as abortions, mummi ication, stillbirths, infertility, weak piglets, and decreased litter size. Pseudorabies Pseudorabies (mad itch) is caused by a DNA herpesvirus that produces a highly fatal disease in swine and may also affect other animals. It is a reportable disease in the USA and has signs similar to those of rabies. Dogs and cats are considered dead-end hosts and die within days of acquiring the virus. The disease is spread by direct contact or indirectly through inhaling the virus. The virus can travel up to a mile and survives for days in certain conditions. It can be inactivated by high temperatures, drying, and sunlight. The virus replicates in the nose, tonsils, and pharynx of infected animals. Signs in neonatal pigs are attributed to the CNS, such as tremors and convulsions, and result in death. Older piglets show respiratory signs, such as anorexia, sneezing, fever, weight loss, or dif iculty breathing. Feline and Canine Baylisascaris Procyonis Baylisascaris procyonis is a common ascarid parasite of raccoons that infects dogs. The adult worms live in the raccoon’s small intestine and eggs pass out of the raccoon in the feces. The single-cell eggs have a thick shell and under optimal conditions, embryonate in the soil to the infective stage. Raccoons ingest the eggs or the hosts that have ingested eggs and become infected. Dogs can either serve as hosts to the adult worm or behave as paratenic hosts and develop neurological signs, such as ataxia, blindness, paresis, or death. Canine adult worm infections can be treated with piperazine, ivermectin, fenbendazole, moxidectin, pyrantel, or albendazole. Dogs can potentially become carriers of this disease and pass it on to humans. This is a signi icant public health concern as Baylisascaris procyonis causes signi icant disease in humans that may result in permanent damage or death. 73 Giardia Felis Giardia felis can be identi ied as a binucleate, lagellated trophozoite. The organism is found in the small intestine and moves down into the large intestine where it forms a resistant cyst wall. The cyst of Giardia felis divides in the large intestine, producing two trophozoites; this mature cyst then passes into the environment through the feces. Cats become infected by fecal-oral contamination and through contaminated water. A cat with an active Giardia infection will have clinical signs such as soft and pale diarrhea and will sometimes have weight loss. Kittens with Giardia will fail to gain weight despite normal appetite. Examination of a diarrhea sample using direct saline identi ies the trophozoite. Centrifugal lotation with the zinc-sulfate method as well as antigen detection assays can be used to detect cysts. Diro ilaria Immitis The heartworm, Diro ilaria immitis , has a life cycle as short as six months. The adult Diro ilaria immitis live in the pulmonary arteries and right ventricles. Micro ilariae are released into the circulatory system and are ingested by mosquitoes that feed on the infected animal. While in the mosquito, the L1 larvae migrate to the stomach and develop into L3 larvae, which then migrate to the mosquito’s mouthparts. When the mosquito feeds, the L3 larvae are deposited in the bite wound and enter into the animal’s bloodstream. Only 10 to 12 L3 larvae are transmitted to the animal by the infected mosquito. The L3 larvae molt to L4 and L5 (adult) larvae and arrive at the pulmonary arteries about three months after the animal is infected. After another two to three months, the adults sexually mature and migrate to the right ventricle. Metabolic Acidosis Metabolic acidosis is caused by the body producing excessive amounts of acid, or the kidneys not suf iciently removing acid from the body. Indications of metabolic acidosis include a decreased blood plasma concentration of bicarbonate and a high hydrogen ion concentration or a low blood pH. Metabolic acidosis may result from syndromes that cause an increase in acids containing chloride, such as diarrhea, addition of medications or luids, or renal tubular acidosis. Another cause is the presence of anions other than chloride in the bloodstream, resulting from conditions such as diabetic ketoacidosis, ingestion of toxic substances, renal failure, lactic acidosis, and hyperphosphatemia. Animals with chronic conditions such as diabetes or hypoadrenocorticism or with renal failure are particularly prone to develop metabolic acidosis, as are animals with acute conditions such as toxin ingestion or diarrhea, or animals receiving carbonic anhydrase inhibitors. 74 Metabolic acidosis is diagnosed through blood serum chemistry testing. Calculating the anion gap may assist in diagnosing metabolic acidosis. The anion gap is calculated as AG= (Na +K)-(HCO3+Cl). A high or a normal anion gap will lead the clinician to suspect diseases such as hypoadrenocorticism, diarrhea (normal anion gap), diabetes ketoacidosis, kidney failure, and lactic acidosis; diarrhea is indicative of a normal anion gap. Depending on the underlying disease condition, the animal may also have high levels of glucose, lactate, phosphate, or potassium or may exhibit azotemia. To correct the disturbance, IV therapy consisting of lactated Ringer’s solution with or without sodium bicarbonate, may be used. ALT and AST Elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) on blood testing indicate that the liver has sustained some damage. These levels become increased due to a number of conditions, including those caused by chemical ingestion, viral, bacterial, fungal, parasitic, or protozoal disease, immune diseases, liver diseases such as hepatitis or cirrhosis, metabolic disturbances, cancer, digestive disorders, or endocrine diseases. ALT is considered to be a liver-speci ic enzyme although it can also be found in muscle and in the brain. AST is found in the liver, lungs, kidneys, brain, muscles, and erythrocytes; it is considered less speci ic to liver damage. In light of the fact that these enzymes can be found in other organ systems, high levels need to be evaluated along with other serum chemistry tests and whole blood cell counts in order to interpret the increased levels correctly. Ascites Ascites is a collection of serous luid in the abdomen that may be either a transudate or a modi ied transudate. Transudate is a low-protein luid that exits the intravascular space because of either increased hydrostatic or oncotic pressure. A modi ied transudate has a higher protein content, which usually occurs either because of hepatic lymph leaking into the transudate or because of in lammation. Causes of transudate include liver disease, protein-losing enteropathy, or kidney disease. Other causes of modi ied transudate include right-sided congestive heart failure, neoplasia, peritonitis, and in cats, lymphocytic/plasmacytic cholangiohepatitis. Occasionally, an effusion of high- protein luid may be found due to serious damage to the biliary tract or urinary tract. Diabetes Mellitus Diabetes mellitus is caused by a de iciency in insulin; this de iciency can either be absolute (Type 1) or relative (Type 2). In type 1 diabetes, the pancreas stops producing insulin; in type 2, insulin is being produced but the body is not 75 responding adequately to the insulin. Insulin de iciency wreaks havoc on the body. The fatty tissues, liver, and muscle are unable to use nutrients properly, which impairs glucose production and use and leads to hyperglycemia; glucose then spills over into the urine, leading to glucosuria. The body tries to adapt by using fat stores for energy and produces ketones; this results in weight loss, fatty liver changes, and possibly ketoacidosis, a life-threatening condition. A cat or dog with undiagnosed diabetes mellitus presents with a particular set of clinical signs. The owner will report that the animal drinks and urinates more, that it seems to be hungrier, and that it has lost weight. The animal may be overweight; a predisposition to developing diabetes mellitus. If the owner has not heeded these signs, the animal may be sicker when brought in for examination, and may be off feed, vomiting, and listless. Examination of the animal may reveal liver swelling (and also jaundice in cats) or trunk muscle wasting and an oily, dandruff- laden hair coat (especially common in cats). Dogs may suddenly develop cataracts, and cats with undiagnosed diabetes mellitus may develop diabetic neuropathy (a plantigrade stance). Blood testing reveals the following: high glucose levels, increases in ALT, AST, and SAP, increased cholesterol levels, and an increase in blood fat. Ketoacidosis Ketoacidosis is a life-threatening emergency in dogs and cats with poorly regulated diabetes mellitus. A lack of insulin causes an increase in fat mobilization from the body stores. The metabolism of fat causes ketone bodies to be formed and the blood to become acidotic. Because of ketone body production and acidosis, the body is unable to maintain luid and electrolytes in the proper amounts; this causes azotemia, electrolyte problems, and dehydration. If not treated, the animal will die. Signs of ketoacidosis in a diabetic animal include increased drinking and urination, lack of appetite, listlessness, vomiting, dehydration, low body temperature, and weakness. Many diabetic animals with ketoacidosis either have poor regulation of their diabetes due to medication or diet problems, other health problems, such as kidney or heart disease or pancreatitis, or an ongoing infection. Congestive Heart Failure Congestive heart failure (CHF) can be attributed to failure of the left side or right side of the heart. In the dog and cat, left-sided failure causes blood to “pool” in the pulmonary circulation system or deprives the body of needed blood. Left sided congestive heart failure can result in disturbed heart rhythm and cause atrial tachycardia, ventricular tachycardia, or atrial ibrillation; these disturbances cause an increased heart rate, while an AV block causes a slower heart rate. The heart muscle itself may not function properly. The most 76 common cause of heart muscle failure is idiopathic dilated cardiomyopathy. High pressure on the heart/associated structures can cause left-sided congestive heart failure, as occurs with subaortic stenosis and hypertension. Other defects leading to left-sided CHF include pericarditis, endocarditis, mitral valve dysplasia, septal defects, cardiomyopathy, thromboembolism, and patent ductus arteriosus. Congestive heart failure (CHF) can be caused by failure of the right side or left side of the heart. The right side of the heart can fail due to a number of reasons: parasitic load, structural defects, toxins, infections, or tumors. Heartworm disease, lung disease, stenosis of pulmonary veins, tumors, Tetralogy of Fallot, and pulmonary hypertension increase pressure on the right side of the heart. The heart muscle can fail due to idiopathic dilated cardiomyopathy or from doxorubicin toxicity. The right ventricle can be prevented from illing because of tricuspid stenosis, tumors, pericarditis, or pericardial effusion. Sometimes the heart rhythm may be disturbed (via AV blocks or supraventricular tachycardia), leading to right-sided congestive heart failure. Review Video: Congestive Heart Failure Visit mometrix.com/academy and enter code: 924118 Clostridium Perfringens Both dogs and cats can have the syndrome known as clostridial enterotoxicosis. This large bowel diarrhea is caused by Clostridium perfringens , which releases an enterotoxin into the intestine that binds to the mucosa, causing cell damage and cell death. In the acute phase, the animal exhibits signs of large bowel diarrhea (frequent small amounts of bloody stool with mucus) that lasts for about one week. Other cases are chronic with intermittent periods of large bowel diarrhea. In addition to diarrhea, the animal may have an increase in gas, vomiting, abdominal pain, and generalized ill health. Treatment revolves around manipulating the diet to reduce clostridial numbers and acidifying the colon; this can be accomplished through a diet high in both soluble and insoluble iber. Antibiotic therapy may also be indicated. Coccidiosis Infection Isospora canis causes coccidiosis in dogs, while Isospora felis causes the disease in cat. The organism sticks with its respective host. The organism causes dogs, cats, kittens, and puppies to have a loose, watery stool, possibly with mucus. In some cases, blood occurs in the stool as well. Puppies may become weakened. A fecal examination reveals the oocysts in the stool sample. Treatment choice is sulfadimethoxine (loading dose of 55 mg/kg by mouth for the irst day, followed 77 by 27.5 mg/kg for four days). Other treatments include fenbendazole (50 mg/kg once daily for three days) or albendazole (25 mg/kg twice daily for two days). Acute Diarrhea There are many causes of acute diarrhea in dogs and cats. These can be grouped into broad categories such as parasitic-induced, drug- and toxin- induced, and infectious, dietary, and miscellaneous causes. Parasites implicated in causing acute diarrhea in the dog and cat are coccidia, ascarids, hookworms, Giardia, and Strongyloides. Infectious pathogens that cause acute diarrhea are Rickettsia, Salmonella, Campylobacter, Bacillus piriformis, E. coli, Clostridial spp., Yersinia, funguses, rotavirus, coronavirus, and parvovirus. Dietary causes of acute diarrhea include eating foods containing lactose or excess fat, abruptly switching foods, eating garbage or spoiled food, or overeating. Many drugs such as antibiotics and analgesics and toxins such as pesticides and insecticides may also cause acute episodes of diarrhea. Syncope Syncope is caused by the inadequate perfusion of the brain, which deprives it of oxygen and needed metabolic substrates. This leads to the temporary loss of consciousness and postural tone. There are a number of causes of syncope, including cardiovascular problems that can cause fainting. Other associated conditions include reduced cardiac output due to cardiomyopathy, infections, narrowed arteries, or veins in the heart or lung, as well as embolism, tumors, or heartworm disease. Nervous system or vasomotor problems such as emotional stress or carotid sinus hyperactivity can also cause syncope in animals. Drugs, hypoglycemia, hypocalcemia, or vascular (blood) disease can cause temporary loss of consciousness. Syncope should be differentiated from neuromuscular diseases such as myasthenia gravis or musculoskeletal disease that may cause an animal to collapse but not to lose consciousness. Cough Re lex A cough is caused when the vagus nerve endings in the larynx, trachea, and bronchi or when the glossopharyngeal nerves in the pharynx are stimulated. Coughs are divided into three broad categories: those caused by upper respiratory tract (URT) diseases, those caused by lower respiratory tract (LRT) diseases, and those caused by diseases of the esophagus or pleura. URT diseases that cause coughing include infections, tumors or foreign bodies in the nasal passages, pharynx, larynx, or trachea, or tracheal collapse. LRT diseases that cause an animal to cough include bronchial infections, in lammation, tumors, or allergies, lung infections, tumors, or edema, aspiration of foreign 78 bodies or substances, congestive heart failure, heartworm disease, pulmonary emboli or thrombi, or pulmonary hypertension. Infective Endocarditis Infective endocarditis is de ined as an infection of the mural endocardium or of the heart valves. In order for infective endocarditis to develop, pathology of the valve or the endocardium must exist that allows bloodborne bacteria to invade and colonize the valves or endocardium. This infection then causes valve destruction and valvular insuf iciency. The most commonly affected heart valves in the horse, dog, and very rarely, the cat, are the mitral valve and the aortic valve, while cattle are more commonly affected with endocarditis on the tricuspid valve. If the aortic valve is involved, left-sided congestive heart failure occurs within a few months. The signs of infective endocarditis include heart murmur, pyrexia, shifting leg lameness, exercise intolerance, lethargy, and cough and/or respiratory distress. If the aortic valve is involved, the examiner might detect hyperdynamic femoral arterial pulses. Diagnosis and treatment of infective endocarditis can be dif icult. Laboratory testing may reveal an active infection (left-shift leukogram, neutrophilia, and monocytosis), while those with a chronic infection may have a normal leukogram or one that shows a mature neutrophilia with monocytosis. Other test results might reveal thrombocytopenia, low albumin, low glucose, or high SAP activity. Because the kidneys are commonly affected by bacteria, urinalysis may reveal proteinuria, casts, hematuria, or pyuria indicating pyelonephritis or glomerulonephritis. Blood cultures should be performed to identify the bacteria responsible for the endocarditis. Echocardiography of the heart will readily reveal aortic valve endocarditis, and chest x-rays may show enlargement of the heart chambers or possibly a defective valve. Skin Lesions Skin lesions must be classi ied in order to accurately diagnose skin conditions. The common primary skin lesions and their typical appearance are as follows: A macule is a reddened or hyperpigmented discoloration of the skin that is less than one centimeter in diameter; a papule is a discrete, small, irm elevation of the skin surface; comedones are blackened blockages of follicles, similar to a human blackhead; a pustule is an elevated, reddened pus- illed bump; a nodule is a large (greater than one centimeter) solid lump elevated above the skin; erosions and ulcers are breaks in the skin with a slightly depressed area. An ulcer erodes the skin deeper than an ulcer directly to the basement membrane. A sinus is an infection that has eroded through the basement membrane. Flea Bites 79 Flea bite hypersensitivity (or allergy) is commonly caused by Ctenocephalides felis (the cat lea) in both cats and dogs. It also causes the condition feline miliary dermatitis. The lea injects the dog or cat with saliva when it feeds on the host. This salvia, rich in many allergens such as amino acids, compounds similar to histamine, and polypeptides, induces hypersensitivity reactions (basophil, Type I, and Type IV). Dogs that have not been previously exposed to lea bites develop IgE and IgG anti lea antibodies. The dog can also develop either an immediate reaction and/or a delayed type of a reaction. It is not entirely understood how the cat responds immunologically to the bite of the lea, but most likely, it is in a manner similar to that of a dog. A dog or cat with a true hypersensitivity reaction to a lea bite displays an itchy dermatitis. The cat may have a variety of clinical signs; the primary skin lesion is a papule that may take on a crusty appearance. The papules are found around the face, neck, and back; this pattern is called miliary dermatitis. The cat experiences intense itching, a rash, and possibly hair loss. In the dog, the allergic reaction causes an intense itching, often starting around the tail head or rear end. This reaction will cause the dog to constantly scratch, chew, and lick at its skin, which may result in hair loss, papules, skin discoloration, and secondary skin infections (hot spots). Campylobacteriosis Campylobacter jejuni causes the disease Campylobacteriosis, which affects dogs and cats, but is particularly prevalent and more severe in puppies less than six months old. The clinical signs of infection with Campylobacter jejuni include diarrhea (either acute or chronic), vomiting, regurgitation, pyrexia, loss of appetite, unkempt appearance, and loss of weight. In pregnant animals, abortions can occur if the fetus becomes infected in utero. The disease can mimic other intestinal diseases such as parasite infection, canine parvovirus, pancreatitis, or salmonellosis. To diagnosis the disease, a fecal smear can be examined under the microscope. This may demonstrate the darting, curved live causative agent. If the smear is gram-stained, the ixed organisms will be gram- negative rods that resemble gull wings. Cultures can be done on the fecal sample as well. Treatment can involve either supportive care alone or supportive care combined with antibiotics. Heartworm Heartworm disease is caused by the parasite Diro ilaria immitis ; the mosquito transmits the organism. The most common mosquito species that transmit Diro ilaria immitis are Culex , Aedes , and Anopheles , although many other species can carry the ilarial worms. The most common companion animal to be infected with heartworm is the dog, although cats and ferrets can also become 80 infected. Outdoor dogs are more likely to be infected. The parasite causes cardiac and pulmonary lesions of variable severity depending upon the number of worms, how long the animal has been carrying worms, how active the dog is, and the immune response the dog has towards the worms. These factors can cause such conditions as congestive heart failure, exercise intolerance, vena caval syndrome, and glomerulonephritis. Rabies Clinical signs in a rabid dog or cat typically involve signs of central nervous system disturbance, primarily behavioral changes; these changes include nervousness, hyperexcitability, irritated attitude, and loss of appetite. A previously docile animal may suddenly become aggressive, or the animal may hide. There is generally what is termed a prodromal stage lasting from one to three days, during which the animal may have intense itching at the wound site and display temperament changes, apprehension, and possibly anxiety. The animal may then proceed to the furious form, with increased activity, biting, changes in the voice, salivation, ataxia, and eventually paralysis and death. More commonly, the animal may have the paralytic form, characterized by hiding, depression, muscle tremors, dif iculty swallowing, and then death. Another form may develop in which the animal survives and becomes a carrier for a long period of time; this is called an unapparent form. Diagnosis of rabies can be dif icult because it has a variety of clinical signs upon presentation. History of exposure, bite wounds, and vaccination history are very important. The disease can mimic other causes of central nervous system disorders such as infections or toxins, canine distemper, listeriosis, pseudorabies, or feline infectious peritonitis. If there is human exposure, the animal should be quarantined for 10 days. If clinical signs develop in the animal during this time period, the animal should be euthanized and the head submitted to the laboratory for testing. The only de initive means to diagnose the disease is through immuno luorescence on brain tissue. Other testing methods that are not commonly used include mouse inoculation, immunoperoxidase staining, and polymerase chain reaction. Nasal Polyps Nasal polyps are pedunculated or elongated in lammatory growths that may resemble neoplasms. Usually, there is a single polyp in a nasal cavity. The outer surface is composed of smooth mucous membrane. The cat can have a very long solitary nasal polyp. The inner layers are composed of a mix of ibrous and myxomatous tissue. There is usually an in iltrate of granulocytes, lymphocytes, and capillaries. Epistaxis, or nosebleed, is usually caused by trauma to the nose or nasal passages, frequently by nasogastric tubes. Other causes include 81 ulcerated nasal tissues, infection of the sinuses or nasal passage, erosion of the nasal arteries from infection, neoplasia, or a fractured bone which has sliced an artery. Glaucoma Glaucoma is an optic disease that is caused by increased ocular pressure, leading to the loss of vision. It can develop as a primary condition from a genetic cause or it can develop secondary to other conditions such as retinal detachment, chronic eye problems, or cancer that develops in the eye. In most dogs, glaucoma develops because of genetic causes. Cats that develop glaucoma typically have another eye problem that leads to the development of glaucoma. Signs of glaucoma can occur in one eye or both eyes. Early signs include eye redness, a dilated pupil, and corneal edema. As the disease progresses, the eye may enlarge, the animal may be in pain, and the lens may luxate. Intraocular pressure increases from the normal range of 10 to 20 mm Hg to over 25 mmHg. Primary or inherited glaucoma is caused when there is an increase in pressure in the eye because of abnormal draining of luid through the iridocorrneal angle; this angle is used to classify the disease into either open angle or narrow angle glaucoma. If the angle where the iris and cornea join is wide, the animal has open angle glaucoma; however, if the iris base is pushed forward, it is known as narrow angle glaucoma. In the dog, narrow angle glaucoma is much more common than open angle glaucoma. Beagles have an inherited tendency to have open angle glaucoma. Open angle glaucoma is more likely to develop slowly over a matter of months; narrow angle glaucoma can cause a sudden increase in pressure in the eye. There are two other forms of glaucoma: goniodysgenesis, or presence of abnormal tissue at the angle, and pigmentary glaucoma, or presence of pigmentary cells blocking the angle. Cataracts Cataracts are de ined as opacity of the lens or its capsule and are typically present in both eyes. The cat most commonly acquires cataracts as a secondary condition after chronic uveitis. Dog can develop cataracts because of genetic defects, as a complication of diabetes mellitus, because of trauma or neoplasia, or secondary to chronic uveitis. Cataracts are the most common cause of blindness in the dog, and usually affect dogs greater than ive years of age. Some common dog breeds affected include Labrador retriever, cocker spaniel, Boston terrier, poodle, Bichon Frise, and miniature Schnauzer. Cataracts should be differentiated from nuclear sclerosis, which is a normal process of aging, or from lens imperfections in younger dogs. The only treatment for cataracts is lens removal. 82  Review Video: Glaucoma and Cataracts Visit mometrix.com/academy and enter code: 279024 Retinal Detachment Retinal detachment occurs when the retina is detached from the underlying tissues and becomes lifted or pulled away from its normal position. There are three different types of retinal detachment: Rhegmatogenous retinal detachment is caused by a tear or break in the retina, which allows luid to low under the retina and then separates the retina from the retinal pigment epithelium (RPE). The RPE is the pigmented cell layer that nourishes the retina. In tractional retinal detachment, scar tissue on the surface of the retina causes it to contract and separate from the RPE. Exudative retinal detachment is caused by an eye disease (in lammation or trauma) that causes luid to leak underneath the retina without any breaks or tears in the retina. Oral Tumors Oral tumors in dogs can be benign or malignant. Cats typically do not have benign oral tumors. In dogs, the most common benign tumor is the epilus, or a tumor arising from the periodontal ligament (squamous cell epithelial cells); it is usually a solitary tumor around the molars (carnassials teeth). An epulis generally has a smooth surface and is closely adhered to the bone. Cats rarely have epulis; the most common benign mouth conditions in the cat are eosinophilic granulomas. The most common malignant mouth tumors in both the cat and dog are squamous cell carcinoma, malignant melanoma, and ibrosarcomas. Careful examination of the oral cavity during a routine physical examination is needed to catch these tumors in their early stages. Fibrosarcomas are the second most common malignant oral tumor in the cat and the third most common malignant oral tumor in the dog. Fibrosarcoma is a locally aggressive tumor that invades the local bone but tends not to spread to lymph nodes or other body organs; it resembles a red growth on the gingival surface that may be necrotic or ulcerated. Larger breed male dogs over seven years of age have a slightly higher incidence of oral ibrosarcomas. Radiographs of the head will reveal bone lysis in the area of the tumor, but to de initively diagnose the condition, a deep biopsy must be submitted for histopathology. Treatment consists of a hemimandibulectomy with wide margins around the tumor. Salivary Mucocele A salivary mucocele occurs when saliva from a damaged salivary duct or gland leaks into the tissues around the duct. It usually presents as a soft, luctuant 83 mass that is generally painless. A salivary mucocele causes an in lammatory reaction in the tissues and become lined with granulation tissue. There are four primary classi ications of salivary mucoceles: sublingual mucoceles (ranula) occur alongside the tongue on the loor of the mouth, and cervical mucoceles occur underneath the jaw or in the upper neck region; this is the most common type of salivary mucocele. Pharyngeal mucoceles are collections of luid in the pharynx. Zygomatic mucoceles occur just below the eye, with the saliva originating from the zygomatic salivary glands. Feline Speci ic Plague Cats contract plague from eating dead rodents infected with Yersinia pestis , the causative agent of plague. This gram-negative bacterium causes an acute and sometimes deadly disease in rodents, rabbits, and humans as well. The lea transmits the bacteria through bites. Once the lea acquires the infection, the bacteria replicate in the lea’s digestive system and multiply to such an extent that they block the lea’s gastrointestinal tract, causing the lea to regurgitate the bacteria and spread it to the animal on which it is feeding. The disease can manifest in three forms: pneumonic, bubonic, or septicemia. After an animal is infected, the bacteria spread to the lymph nodes by the lymphatic vessels; the inoculated lymph nodes are then called buboes. If the organism spreads from the lymph nodes to other body organs, it is then called septicemia. Pneumonic plague develops either through septicemia or from inhaling aerosolized droplets from an infected animal. Oral Squamous Cell Carcinoma Oral squamous cell carcinoma is the most common tumor of the cat; it is a malignant tumor and invades the bone. The affected tissue appears irregular, is elevated, and is frequently necrotic and ulcerated. It is locally aggressive and typically does not spread to lymph nodes. In addition to a red, ulcerated spot on the gingival surface, the cat may have dif iculty eating, excessive salivation, and bad breath, and may lose weight. The teeth surrounding the tumor may be loose as well. Biopsy is needed for diagnosis. Treatment involves radical surgery (partial mandibulectomy or maxillectomy) and radiation therapy. Frequently, the tumor will reoccur within a year, and the cat will die from anorexia and extreme weight loss. 84 Hyperthyroidism Hyperthyroidism is a metabolic disease that affects middle-aged and older cats. It is the most common endocrine disorder in the cat. Enlarged nodules on the thyroid gland secrete thyroxine (T4) and triiodothyronine (T3). These enlarged nodules are usually benign tumors called adenomas; rarely is the disease caused by a malignant adenocarcinoma. Thyroid hormones affect most organs in the body. The heart can become enlarged. Hypertension can occur, causing damage to the heart, kidney, brain, and eyes. The gastrointestinal tract is affected as well, leading to malabsorption, diarrhea, and liver damage. The cat may have behavioral changes and appear anxious or have a ravenous appetite. All these effects are due to the increased metabolism caused by the high circulating levels of the thyroid hormones. The clinical signs of a cat suffering from hyperthyroidism are attributed to the increase in metabolism created by high levels of thyroid hormone. The cat will lose weight despite a greatly increased appetite; it may have diarrhea, may become more thirsty than normal, have increased urine production, become hyperactive, and may vomit, and its coat may appear greasy and matted. Physical examination of a cat with hyperthyroidism will reveal an enlarged thyroid gland, heart murmur, increased heart rate, and poor body condition. Tests usually run to diagnose hyperthyroidism include complete blood count (CBC), blood chemistry, and a thyroid function tests. Most cats with hyperthyroidism will have an elevated level of T4 thyroid hormone. Review Video: 7 Symptoms of Hyperthyroidism Visit mometrix.com/academy and enter code: 923159 Otodectes Cynotis Otodectes cynotis is a common mite that lives in the ear canal of cats. Kittens are commonly plagued by this mite, which causes irritation and a hypersensitivity reaction. Typical signs in a kitten include pruritis around the head and ears. The ears have a thick, dark, crusty material in the outer ear commonly extending into the ear canal itself. Many kittens will have scratch marks about the ear due to the intense itching. Diagnosis relies on ear swabs taken to remove exudates and then examining the exudates with mineral oil under the microscope to identify the mite. Treatment consists of thoroughly cleaning the exudates out of the ears, application of a topical product in the ear until cure is achieved, and treating the environment with pesticides. Alternatively, ivermectin may be used off-label. 85 Chlamydia Psittaci Chlamydia (Chlamydia psittaci ) causes a chronic respiratory infection in cats, with kittens aged two to six months most commonly affected. The bacterium multiplies in the upper and lower respiratory tract, causing signs referable to these areas. C. psittaci is also able to colonize the reproductive and gastrointestinal tracts as well. In the respiratory tract, the clinical signs seen in the cat include bronchitis, bronchiolitis, and rhinitis. All these symptoms are minor and cause coughing, sneezing, and watery eyes. Sometimes a cat will also get pneumonia from C. psittaci. Other disease conditions to consider when confronted with a cat with these signs are feline calicivirus (ulcerative stomatitis), feline viral rhinotracheitis (ulcerative keratitis), feline reovirus infection (very mild disease only in upper respiratory tract), or other bacterial causes of pneumonia. Tetracycline drugs are the agents of choice when treating a cat with Chlamydia. Biliary Tract Disease Cats can suffer from diseases of the biliary tract; speci ically, cholangitis and cholangiohepatitis, or in lammation of the biliary ducts, the intrahepatic ducts, and the liver. There are three main types of disease: Lymphocytic and lymphocytic-plasmacytic types are caused by an immune reaction of the body; the suppurative type is most likely caused by a bacterial infection that may trigger an immune response and a lymphocytic and lymphocytic-plasmacytic reaction. Many cats with this in lammation of the biliary system and liver also have concurrent problems such as in lammatory bowel disease, cholecystitis, or pancreatitis. They may also have stasis of the bile, which may block the ducts or breed bacteria. Stasis is more common in middle-aged or older cats. Chronic Diarrhea Cats can have chronic diarrhea for many reasons, including parasites, fungus, in lammatory diseases, obstructions, infections, metabolic disorders, and dietary causes. Parasites that cause diarrhea in cats include Toxoplasma gondii, Cryptosporidium, Diro ilaria immitis, Toxocara cati, and Giardia. Fungus infections that cause chronic diarrhea in cats include aspergillosis, histoplasmosis, mycobacteria, and phycomycosis. In lammatory conditions such as granulomatous enteritis, lymphoplasmacytic enterocolitis, and eosinophilic enteritis/hypereosinophilic syndrome can cause chronic diarrhea. Obstructions from cancer, foreign bodies, strictures, or an intussusception can lead to diarrhea in the cat. Many infectious agents cause chronic feline diarrhea. Viruses (feline leukemia virus, feline infectious peritonitis virus, and feline immunode iciency virus) and bacteria (Salmonella, Yersinia, Clostridium, and Campylobacter ) are major causes of diarrhea. Metabolic disorders such as 86 hyperthyroidism, diabetes, and kidney and liver disease have diarrhea as a symptom. Diets (sudden changes, intolerances, garbage eating) can also cause chronic diarrhea in cats. Cryptococcosis Cryptococcosis is a disease of cats that manifests as upper respiratory signs (rhinitis and nasal discharge), eye signs (retinal detachment, dilated pupils, optic nerve in lammation, or chorioretinitis), skin lesions, or neurological disease. The respiratory signs are more common in this disease, which is caused by inhalation of the fungus Cryptococcus neoformans, a yeastlike organism that tends to invade the upper respiratory tract (sinuses and nasal cavity). Cryptococcus neoformans is found in bird droppings, especially those of pigeons, and in soil. Given the right conditions the organism can live in the soil for up to two years. Treatment is with antifungals: itraconazole or luconazole given in the food for one or two months after resolution of clinical signs. Cytauxzoonosis Cats can suffer from the disease Cytauxzoonosis, which is an infection with the protozoa Cytauxzoon felis. This rare disease is spread by tick bites (Dermacentor variabilis ) and occurs in the bobcat and the Florida panther. The organism has an af inity for the vascular systems of many organs: brain, bone marrow, lungs, kidneys, liver, and spleen. After infection, within one to three weeks the cat will exhibit clinical signs. Cats contracting the protozoa will be severely ill with anemia, fever, dehydration, depression, enlarged spleen and liver, and icterus. The protozoa multiply and cause the body’s macrophages to swell and to line the vascular system, which results in congestion in various organs. The disease is almost 100% fatal. Use of antiparasiticals to prevent tick bites may bene it cats in endemic areas. Hypertrophic Cardiomyopathy Cats can suffer from hypertrophic cardiomyopathy, which causes clinical signs such as respiratory distress, collapse, exercise intolerance, cough, or sudden death. These signs are attributed to the hypertrophy of the left ventricular wall or the interventricular septum. This enlargement of the left ventricle causes high illing pressures in this ventricle as well as arterial enlargement. The respiratory tract is also affected, leading to pulmonary hypertension and edema. Other problems include formation of thromboembolism due to blood stasis in the left atrium, heart arrhythmias, renal problems due to poor blood perfusion, and congestive heart failure. The heart, lung, and circulatory problems can cause signs in other body systems such as a weak femoral pulse; an aortic thromboembolism can cause sudden rear limb paralysis. If this occurs, 87 the animal will have cold limbs, no femoral pulse, and bluish nail beds and foot pads. Ringworm A sizeable number of cats suffer from ringworm (dermatophytosis). Dermatophytosis is caused by the fungi Microsporum canis , Microsporum gypseum , and Trichophyton mentagrophytes. The clinical signs of ringworm may include hair loss in a circular pattern, itching, redness, or scaling/ laking skin. Long-haired cats seem to be more likely to be infected. Cats can have the ringworm fungus but remain asymptomatic and can spread the disease to other animals and humans. The fungus lives in the super icial layers of the skin, in the hair and the nails. It grows in the keratinized layers after incubating for one to four weeks. Diagnosing ringworm relies on clinical examination combined with fungal culture. Gingivitis/Stomatitis Syndrome Feline gingivitis/stomatitis syndrome cause clinical signs of drooling, anorexia, halitosis, and oral pain. The physical examination reveals a cat suffering from gingival in lammation, stomatitis, pharyngitis, palatitis, and in lammation of the caudal fauca. Treatment of feline gingivitis/stomatitis syndrome begins with a thorough dental examination and prophylaxis. Teeth with end-stage periodontal disease and odontoclastic resorptive lesions should be removed. A biopsy of active lesions should also be taken and submitted for histopathological examination. Home care should include daily tooth brushing, chlorhexidine application, and antibiotic therapy using clindamycin, tetracycline, or metronidazole. Some cases are refractory to these therapies. Methylprednisolone acetate can be given every month to control the in lammation. In extreme cases, removal of all the teeth caudal to the canines can be attempted. Oral Squamous Cell Carcinoma The most common oral neoplasia of the cat is squamous cell carcinoma (SCC). The presenting clinical sign is most commonly an oral mass along with ptyalism; other signs include dysphagia, halitosis, and weight loss. Physical examination may reveal loose teeth, indicating bone lysis. This is an extremely aggressive and invasive malignant tumor. A deep incisional biopsy should be taken and submitted for histopathology. Chest x-rays should also be taken to check for pulmonary metastasis, and any enlarged lymph nodes should be aspirated for cytology. Other diagnostic testing such as CBC, chemistry, and urinalysis should be performed to assess health status. Treatment is not generally successful for this particular neoplasm, and in spite of treatment, most cases recur in six months. 88 Eosinophilic Granuloma Complex The term eosinophilic granuloma complex is used to encompass three different syndromes in the cat: indolent ulcer, eosinophilic plaque, and eosinophilic granulomas. These conditions are characterized by an in iltrate of eosinophils into the epithelial tissue. All three may occur as a result of genetics or as an allergic, in lammatory condition and may come and go. An indolent ulcer is usually a raised area on the upper lips that tends to ulcerate. Eosinophilic plaques occur on the body, speci ically, the armpit, the thighs, and the inguinal and perineal areas, and appear as hairless, reddened, moist patches. An eosinophilic granuloma can occur anywhere on the body. The lips and foot pad may swell and be painful and oral ulcerations may occur that cause drooling and dif iculty eating. The body lesions may be white or yellow ulcerated areas; those on the caudal thigh may be linear granulomas. Heartworm Infection The cat has a different response to heartworm infection than the dog. Adult heartworms live in the cat from 18 to 24 months. The average worm burden is one to three worms; most cats do not have signi icant pulmonary hypertension or heart problems associated with this worm burden. Most of the symptoms displayed by an infected cat revolve around the lungs. The adult larva (L5) develops in the right and left pulmonary arteries and caudal lung lobes where most of the damage to the lungs occurs. In the cat, most of the L5 larva dies, and there is a strong in lammatory and eosinophilic response. As the worms grow, further damage occurs to the pulmonary arteries and the capillary beds. In response to this in lammation, the cat may exhibit asthma-like symptoms such as coughing and dif iculty breathing. The cat has a different response to heartworm infection than the dog. Adult heartworms live in the cat from 18 to 24 months. The average worm burden is one to three worms; most cats do not have signi icant pulmonary hypertension or heart problems associated with this worm burden. Most of the symptoms displayed by an infected cat revolve around the lungs. The adult larva (L5) develops in the right and left pulmonary arteries and caudal lung lobes where most of the damage to the lungs occurs. In the cat, most of the L5 larva dies, and there is a strong in lammatory and eosinophilic response. As the worms grow, further damage occurs to the pulmonary arteries and the capillary beds. In response to this in lammation, the cat may exhibit asthma-like symptoms such as coughing and dif iculty breathing. FIV Feline immunode iciency virus (FIV) is a lentivirus somewhat similar to the human immunode iciency virus, although it does not infect humans. It is passed 89 from cats to cats primarily through bite wounds, as the virus is found in the saliva. Pregnant cats can transmit the disease virus to unborn kittens in the uterus or through the milk. Once infected, a cat is infected for its lifetime. An infected cat becomes very prone to infections via immune system suppression. After it is initially infected, there is a brief period when the cat’s body responds with fever and swelling of the lymph nodes, along with neutropenia. The body then recovers and the cat appears normal for months to years before other signs appear. The clinical signs of feline immunode iciency virus (FIV) are extremely variable and the immune suppression can make the animal susceptible to many different disease conditions. The virus reproduces in the T-lymphocytes in the lymph nodes. The signs that the virus has compromised the cat’s health include gingivitis and stomatitis, weight loss, unkempt hair coat, anorexia, and fever. The cat can also have skin infections, bladder infections, or upper respiratory tract infections; ocular in lammation and persistent diarrhea can be a problem as well. The disease can affect the neurological system and lead to behavioral changes or seizures. Arthritis, cancer, and anemia can also occur. The disease course can wax and wane, with periods of normal health interspersed with clinical signs. Testing for feline immunode iciency virus (FIV) antibodies is the primary means to diagnose the disease. If the test is positive, the cat is infected with FIV, as cats remain infected for life. Kittens less than six months of age that test positive should be retested, as kittens born to an infected mother can transmit her antibodies through the milk to the nursing kittens. Most kittens born to an infected mother will not be infected with the virus. It takes from two to three months after infection for the body to mount an antibody response. If a cat is bitten by another cat with an unknown FIV status, it should be test at least two months after the bite in order to determine if it is infected. Cats that have suffered from FIV for a long time may have a negative test result due to the severe immune compromise. FIP Feline infectious peritonitis (FIP) is a disease caused by a pathogenic strain of the feline coronavirus. The coronaviruses that affect cats are either the pathogenic strain or the feline enteric coronaviruses that do not cause disease or cause a very mild intestinal disease. If a cat is infected with the pathogenic strain of feline coronavirus, it will typically not display any symptoms or signs at the time it is infected other than an immune response that can be demonstrated by detecting antibodies in the blood. The clinical manifestation of FIP can take months to years to develop; however, only a small percentage ( ive to 10 90 percent) of cats that test positive will develop FIP. After clinical signs occur, death will ensue within a matter of weeks. Feline infectious peritonitis (FIP) only occurs in a small percentage of cats infected with the coronavirus responsible for FIP. In these cats, the virus invades the white blood cells, with the assistance of the antibodies developed by the immune system in response to the viral infection. The infected cells then go to various body organs, and an in lammatory reaction occurs around the vessels where the cells have lodged; this typically occurs in the brain, kidney, or abdomen. FIP develops according to how the immune system responds to infection. There is a “wet” form caused by a weak cell-mediated response and a “dry” form caused by a moderate cell-mediated response. Carriers are either healthy or recover due to a strong cell-mediated response. The signs of feline infectious peritonitis (FIP) vary depending on the form of disease. For either type (wet or dry), general symptoms include malaise, anorexia, fever, weight loss, and unkempt hair coat. The wet form causes a sero ibrinous peritonitis or pleuritis due to vasculitis, which allows serum and protein to leak from vessels. It can also cause ascites and effusions around the heart. Due to luid accumulation, the abdomen will enlarge. The dry form causes a granulomatous reaction involving the internal organs, eye, and/or brain. The dry form is so-called as there is no effusion present. The disease can be dif icult to diagnose, although it should be strongly suspected if a cat has a fever that does not respond to antibiotic therapy. In addition, diagnostic tests are not speci ic enough to differentiate between the pathogenic coronavirus and the enteric coronavirus. De initive diagnosis is made upon biopsy of necropsy samples. FeLV Feline leukemia virus (FeLV) is a retrovirus that causes a persistent infection in less than two percent of cats who contract the virus. There are three subtypes: A, B, and C; cats spread subtype A. The virus invades the tonsils and pharyngeal lymph nodes and infects B lymphocytes and macrophages, which spread the virus to various body tissues. In the cells, the retrovirus inserts copies of its genetic material into the host cells by use of reverse transcriptase. At the point of irst infection, the immune systems of most cats eliminate the virus; a smaller portion will remain viremic for a period of time but eventually recover without any sign of infection. The two percent that are unable to mount an immune response remain viremic and may develop disease conditions associated with FeLV. The signs of feline leukemia infection in the cat vary depending on the body tissues affected by the virus. It is the most common cause of cancer in the cat 91 and due to its attack on the immune system, leaves affected cats vulnerable to opportunistic infection by other viruses and bacteria that normally do not cause illness in cats. Some of the signs exhibited by infected cats include: gingivitis and stomatitis; recurring infections of the bladder, upper respiratory tract, and the skin; constant fever; anorexia; weight loss; generalized lymphadenopathy; unkempt appearance; constant diarrhea; signs attributable to the CNS; ocular infections or problems; and reproductive failure or abortion in intact females. The signs can wax and wane or they can lead to death. A cat with clinical signs suggestive of FeLV requires a complete examination performed to rule out other disease conditions that mimic the various manifestations of FeLV. Diseases to include on the differential diagnosis list include feline infectious peritonitis, feline immunode iciency disease, other cancer causes, haemobartonellosis, or bacterial, fungal, or viral diseases. An ELISA (enzyme-linked immunosorbent assay) test can be performed in the veterinary clinic that will detect primary and secondary stages of viremia. It is recommended that the test be repeated in three months to make sure the cat is persistently infected. At this point, an IFA (indirect immuno luorescent antibody assay) test can be performed to positively identify persistently infected cats. Both tests detect the p27 FeLV antigen. Neoplastic FeLV One of the disease manifestations of a cat persistently infected with feline leukemia virus (FeLV) is the neoplastic form. This is a lymphosarcoma that may develop in the gastrointestinal tract, the bone marrow, a generalized multicentric form, and cancer of the thymus. In the gastrointestinal tract, masses can be found in the intestines and mesenteric lymph nodes. The bone marrow (lymphoid tissues) produces cancerous lymphocytes that cause generalized lymph node enlargement and enlargement of the spleen and liver. Young cats frequently contract the multicentric form, which can cause kidney cancer along with enlargement of the liver and spleen. The thymus can become cancerous and enlarge, causing dif iculty with breathing and eating. Another neoplastic form is myeloid leukemia, which affects various bone marrow cells, causing lymph node, liver, and spleen enlargement. Non-Neoplastic FeLV The non-neoplastic form of feline leukemia virus (FeLV) can cause immunosuppression, glomerulonephritis, or reproductive disorders. When FeLV causes immunosuppression in the cat, the cat may exhibit such recurring disease conditions as periodontal disease, upper respiratory tract infections, and infections around the claws; cats may also have poor wound healing and be chronically infected with any number of viruses, bacteria, or fungi. Female cats 92 with FeLV that are not spayed can have multiple problems with pregnancy, including abortions, stillbirths, or failure to maintain a pregnancy. Kittens born to FeLV-infected mothers may be weak and sickly and suffer from fading kitten syndrome. Another possible manifestation of FeLV is glomerulonephritis, in which antigen-antibody complexes are lodged in the kidney, leading to renal failure. Feline Panleukopenia Feline panleukopenia is an acute viral disease lasting for ive to seven days. It is caused by the feline parvovirus a single-stranded DNA virus. The disease is highly contagious and the virus is highly stable in the environment and can last for years in favorable conditions. The virus spreads via infected secretions, urine, and feces and attacks the actively dividing cells in the blood and intestinal tract; this causes vomiting and diarrhea, leading to severe dehydration and lethargy. Most of the white blood cells in the body are lost; leukocyte counts typically drop from 500 to 3000 cells/microl. If a pregnant cat contracts feline panleukopenia, the virus will attack the fetal or neonatal nervous system. The virus destroys the cells of the cerebellum and retina. Feline panleukopenia strikes suddenly in unvaccinated cats. Some cats will have mild symptoms; other will have a severe, sudden illness. The main symptoms are an extreme depression (sitting hunched up), hiding, dehydration, vomiting, diarrhea, nasal discharge, conjunctivitis, abdominal pain, and fever. Kittens can be infected in utero or soon after birth; they display central nervous system symptoms such as ataxia and gait abnormalities or problems with vision (retinal dysplasia). Other differential diagnoses include intestinal foreign bodies, feline infectious peritonitis, poisonings, herpesvirus infection, feline calicivirus, salmonellosis, or feline leukemia virus infection. Laboratory testing will reveal a severe panleukopenia (500 to 3000 cells/microl leukocytes). The feline panleukopenia virus antigen is detected on the canine parvovirus antigen fecal immunoassay. Serological testing on paired serum samples are also useful in arriving at a de initive diagnosis. Periodontal Disease Periodontal disease is a very common disease of the teeth affecting the majority of cats over the age of six years of age. It can be classi ied into ive different stages of disease: At the beginning of the disease process (Stage 1), gingivitis occurs, which is caused by an accumulation of plaque; Stage 2 means the gingivitis is more advanced, but is still reversible. Stage 3 is the irst stage of advanced periodontal disease, with gingival in lammation and deep pocket formation. During Stage 4, the pockets become deeper, there is loss of bone, and 93 teeth become loose. At Stage 5, the only treatment option is to remove teeth to relieve the pain, discomfort, and infection caused by neglected dental care. Odontoclastic Resorptive Lesions Feline odontoclastic resorptive lesions are common dental lesions that are very painful. The lesions include a loss of dental tissue at the neck of the teeth or the crown, various stages of resorption of dental tissue, and bright red gingival in lammation. Stimulation of these lesions elicits a painful response from the affected cat. In addition to the pain, the cat generally drools and does not want to eat. The cause is not known but it is suspected that the odontoclasts, which resorb tooth structure, become active; this activity cannot be prevented. The lesions have been classi ied into ive stages: lesions only on the enamel, lesions that extend into the dentin, lesions that extend into the pulp, and lesions that cause crown destruction. Once the lesions extend into the dentin, it is recommended that teeth be extracted, as restoration attempts usually fail. Canine Speci ic Coccidioidomycosis Coccidioidomycosis is a fungal infection found in dogs caused by the fungus Coccidioides immitis. Only a small amount of fungal spores are needed to cause disease and are typically introduced into the body through inhalation. The spores are found in arid regions of the southwestern United States in the lower Sonoran life zone (California through Texas). The fungus causes fever, weakness, lack of appetite, coughing, and listlessness. Occasionally, other body systems such as the joints may be painful and stiff. Treatment for this severe and life-threatening disease is long-term and aggressive use of an antifungal. Antifungals used in the treatment of coccidioidomycosis include ketoconazole (10-30 mg/kg three times daily) for one year or amphotericin B (.5 mg/kg IV every other day) until an accumulative dose of 8-10 mg/kg is given. Chronic Diarrhea Dogs with chronic diarrhea pose a diagnostic challenge. One of the irst things the practitioner needs to do is localize the cause. This can be done by categorizing the diarrhea as small intestinal or large intestinal diarrhea. Based upon this characterization, different conditions can be investigated as the cause of the diarrhea. Small intestinal diarrhea is characterized by large-volume diarrhea, occasional vomiting, melena (but no frank blood or mucus), and weight loss. This type of diarrhea has a number of causes, including metabolic disorders, maldigestion, primary disease of the small intestine (within the intestine itself or due to parasites or infection), or diet. Large-bowel diarrhea is characterized by increased defecation frequency but in smaller amounts with 94 each defecation, blood and mucus in the stool, straining, and an urgent need to defecate. Causes of large-bowel diarrhea include dietary causes, metabolic disorders, intestinal problems (in lammation, cancer), parasites, or infection. Cruciate Disease Cruciate disease is a common surgical disease of dogs. The anterior cruciate ligament (ACL) can tear, either partially or fully, leading to lameness, pain, and arthritis. Animals that are obese, are a large breed, are vigorous athletes, or have a luxated patella or poor overall con irmation may be more prone to this injury. Cruciate disease may be caused by acute trauma or by a degeneration of the ligament. The ligament provides stability to the sti le joint by limiting rotation and displacement of the tibia and also functions to prevent hyperextension. The most common way the ligament tears is by traumatic forces that cause the sti le to hyperextend or by forceful rotation while the sti le is partially lexed. ACL Diagnosis of a torn anterior cruciate ligament (ACL) requires observing the clinical signs (lameness, pain, reluctance to walk), taking a thorough history of the inciting cause of the clinical signs, and obtaining a thorough physical examination. The most de initive way to diagnose a rupture or partial tear is through demonstrating a cranial drawer motion; this should be tested while the leg is extended, lexed, and at the normal standing position. Some animals, especially excitable, painful, or frightened dogs, will need to be sedated in order to get an accurate result. A negative result in light of clinical signs and history does not rule out a tear or rupture. Palpating the joint will demonstrate a joint effusion along with thickening of the joint capsule. Longer standing cases may have muscle atrophy. Pododermatitis Dogs suffering from pododermatitis (also known as interdigital dermatitis) can either have problems in one isolated spot on one foot or the problem can be widespread. In some cases, the cause is unknown (idiopathic). If only one foot is affected, the practitioner may suspect a neoplastic condition, imbedded foreign bodies such as plant awns, slivers of wood, or tree needles, or a possible case of osteomyelitis. If more than one foot is affected, the cause might be a systemic disease condition, such as a parasitic infection that also causes foot lesions (demodicosis, hookworm, or heartworm), a metabolic disease (hyperadrenocorticism or low thyroid levels), infections from fungus or bacteria, an allergic or sensitivity reaction, chemical burns, trauma, immune system problems (pemphigus, systemic lupus erythromatosis, or pemphigoid), or low levels of zinc. 95 Dermatomyositis One breed-speci ic disease of dogs is dermatomyositis. This disease is an inherited condition that causes slight skin lesions and mild myositis to severe skin ulceration and scaring and muscle atrophy. It can be triggered by sunlight, stress, or factors related to the female reproductive cycle. Collies, Shetland sheepdogs, and their crosses are breeds affected by dermatomyositis. The lesions typically appear when the puppy is between two to six months of age. The dermatitis usually appears irst on the bony prominences of the distal extremities, the tail tip, the face (eyes and lips), and the inner tips of the ears. Varying degrees of redness, scaling, hair loss, ulceration, and crusting occur in these areas. Severity of muscle in lammation may also vary from mild lameness to impairment of the muscles used for eating, drinking, and swallowing. Muscles on the face and jaw may even waste away. Nasal Dermatoses The causes of nasal dermatoses that a practitioner is likely to encounter in the canine include the following: demodicosis, contact dermatitis (from plastic food dishes), dermatophytosis, nasal pyoderma, discoid lupus erythematosus, dermatomyositis, systemic lupus erythematosus, squamous cell carcinoma, basal cell carcinoma, ibrosarcoma, trauma, zinc-responsive dermatosis, pemphigus foliaceus, pemphigus erythematosus, drug sensitivity, and granulomas. Some speci ic breed predilections for nasal dermatitis include Alaska malamutes; dogs under a year old and Siberian huskies are prone to zinc- responsive dermatosis. Young dogs less than a year old are more like to suffer from demodicosis and dermatophytosis. Dermatomyositis is more likely to be found in young dogs, collies, and Shetland sheep dogs. Collies, German shepherds, and Shetland sheep dogs are predisposed to discoid lupus erythematosus and systemic lupus erythematosus. Atopy Atopy is a common condition in the dog that usually develops in the irst years of life; this is the tendency for the dog’s body to develop skin hypersensitivity to environmental allergens. Allergens commonly implicated in canine atopy include molds, pollens (weed, grass, and tree), dust mites, and animal dander. The typical reaction includes exposure to the allergen, which is associated with an IgE. After repeated exposure to the allergen, its IgE then binds to skin mast cells, which degranulate to release compounds causing intense itching. The hypersensitivity reaction can be year-round or seasonal depending on the allergen cause. As the years progress, atopy becomes worse and a seasonally dependent allergy may become a year-round allergy. Differentials to atopy 96 include lea bite hypersensitivity, food allergy, contact dermatitis, yeast allergy/infection, or mange. Babesiosis Babesia gibsoni, a protozoan, causes babesiosis, a severe red blood cell disease in dogs. Another type, Babesia canis , causes a mild disease in adult dogs but can kill exposed puppies. In dogs with Babesiosis causing red blood cell destruction and anemia, the clinical signs include anorexia, pale mucous membranes, listlessness, fever, vomiting, discolored urine, increased heart and respiration rate, enlarged spleen, and icterus, all generalized signs of anemia. Blood work reveals a hemolytic anemia, as indicated by spherocytes, anisocytosis, and polychromasia. Diagnosis is based upon demonstrating the organism Babesia in the blood; however, these are sometimes dif icult to ind. Other tests to help diagnosis the condition include titers, Coombs’ testing, and indirect luorescent antibody tests. Blastomycosis Blastomyces dermatitidis causes blastomycosis, a systemic fungal infection affecting the lungs, male genitalia, eyes, and/or skin of dogs. Hunting or sporting breeds of dogs are especially prone to acquiring this fungus, as they are more exposed to environments harboring Blastomyces through inhaling the fungus or through skin wounds. Presentation of clinical signs depends upon the area affected. Skin lesions manifest as abscesses or thickened areas that ooze luid and are ulcerated. If bone is invaded from the skin, an osteomyelitis will occur; if this occurs on the leg, the dog will be lame. Some male dogs have lesions such as skin lesions in the testicles or have an enlarged prostate. Ocular infection presents as a uveitis. In the respiratory tract form, a dog presents with dif iculty breathing, fever, cough, enlarged lymph nodes, pneumonia, and weight loss. Bordetella Bronchiseptica Kennel cough or infectious tracheobronchitis is caused by Bordetella bronchiseptica and is a major respiratory pathogen of dogs. It is a gram-negative bacterium that is transmitted through the air and through contaminated fomites. Bacteria colonize the respiratory tract epithelial cells and excrete endotoxins and exotoxins that harm the respiratory tract and suppress the immune system. The primary clinical sign is a paroxysmal hacking, dry cough that becomes worse with exercise or palpation of the throat. Generally, the disease is self-limiting, although antibiotics and other medications are used to ease symptoms. Antibiotics most effective against Bordetella include erythromycin, azithromycin, tetracycline, clarithromycin, and chloramphenicol. Other antibiotics include trimethoprim-sulfamethoxazole and cephalosporins. 97 To control coughing, limit the dog’s exercise and use bronchodilators and antitussives. Vaccinations (modi ied live, whole cell bacterin, extracted cellular antigens) are available in either intranasal or injectable form. Distemper Canine distemper is diagnosed based on clinical signs and laboratory testing. Clinical signs are variable, from no visible signs to a severe disease with central nervous system signs. A diphasic fever occurs; the irst three to six days post- infection and the second several days later, along with eye and nose discharges. Generalized signs include anorexia and listlessness. Some dogs experience secondary gastrointestinal, ocular, and respiratory signs as well. The CNS component manifests as seizures, myoclonus, ataxia, paralysis, muscle tremors, and paresis. Laboratory work-up reveals lymphopenia and thrombocytopenia during the early acute phase; monocyte numbers may increase. Other tests to pinpoint the virus include ELISA and PCR. Dogs with CNS signs may have increased mononuclear cells and protein in the cerebrospinal luid. Causes of Abortion The causes of abortion in the dog can be categorized as follows: fetal defects, reproductive organ dysfunction, infectious organisms, and hormonal dysfunction. Fetal defects that cause a bitch to abort are chromosomal defects inhibiting life and fetal organ defects. Problems with the bitch’s reproductive organs may also interfere with carrying a litter, including lysis of the corpora lutea associated with use of prostaglandins, estrogens, high dosages of glucocorticoids, or drugs toxic to the embryos, as well as trauma, neoplasia, use of chloramphenicol, pyometra, and cystic endometrial hyperplasia. A number of infectious agents are abortogenic, including viruses such as distemper, parvovirus, and herpesvirus. Bacteria that cause canine abortions include E. coli , Campylobacter , Streptococci , and Brucella canis. Other organisms that cause abortion in the dog are toxoplasma, Ureaplasma, and mycoplasma. Hormones can also cause abortion in the dog. A dog with uncorrected hypothyroidism or with hypoluteoidism can abort a litter. Diaphragmatic Hernia A diaphragmatic hernia is a surgical emergency. In dogs, diaphragmatic hernia may result from congenital defects, or more commonly, from trauma. Being hit by an automobile is the primary traumatic cause of the hernia. The diaphragm muscle tears or ruptures, leading to the intestinal organs bulging through the opening and into the chest cavity. Hypoventilation results from the lungs not being in normal contact with the parietal pleura or due to fractured ribs. Bulging of the abdominal organs and luid accumulation also contribute to hypoventilation. In addition, the lungs may collapse or be bruised. The heart 98 muscle may also be traumatized, leading to cardiac problems. As a result of pain, trauma, and lung issues, the animal typically goes into shock and may die before surgical intervention. Physical signs include respiratory distress, muf led heart sounds, and shock. Otitis Externa Otitis externa frequently occurs in the dog. It is an in lammation of the skin lining the external ear canal and can be either acute or chronic. The ear becomes reddened, there is an increase in exudate from the ear, and the dog’s skin is pruritic and/or painful. Some dogs are prone to developing ear infections due to poor ear canal conformation or excessive hair in the ear canal. Bacteria (staphylococci or streptococci) or fungus (Malassezia pachydermatis ) are common causes of otitis externa infection. The ear canal should be thoroughly examined to assess the degree of infection and to make sure the tympanic membrane is intact, and sedation should be used if the ear is painful or the dog is uncooperative. Therapy should only be initiated once the cause of infection is determined. Typically, ears should be cleaned of exudate before medications are placed in the ear canal. Ectropion Ectropion is a condition of the eyelids in which the eyelid margins either roll in or out; this causes the underlying conjunctiva to become exposed and causes problems with tearing. The dog presents to the veterinarian with eyelid redness, thick discharge from the eye, and often secondary bacterial infections or even corneal ulceration. This condition may be due to genetics; certain breeds are predisposed to developing ectropion such as bloodhounds, the St. Bernard, and the Mastiff. Other causes include hypothyroidism, nerve paralysis, or myositis. In animals with minimal symptoms, medical care including facial cleansing, treatment of any underlying medical conditions, eye medication, and observation may be all that is needed. Other more severe cases may need surgery such as eyelid shortening or a face lift procedure in order to prevent loss of vision. Hypoadrenocorticism Hypoadrenocorticism, otherwise known as Addison’s disease, is a fairly rare disease found primarily in young, female dogs. Primary hypoadrenocorticism is most likely caused by an autoimmune destruction of the adrenal cortex. This destruction results in the body becoming de icient in cortisol (glucocorticosteroid) and aldosterone (mineralocorticoid). Cortisol is released from the adrenal glands in response to ACTH produced by the pituitary gland. It is necessary in a number of important bodily functions, including glucose metabolism, regulation of blood pressure, immune function, and insulin release, 99 and aids in the in lammatory response. Aldosterone works in the kidney to increase the reabsorption of sodium and water and to release potassium. These actions help the body to maintain a constant blood pressure. Hypoadrenocorticism (Addison’s disease) may cause non-speci ic signs. A typical sufferer is a young to middle-aged female dog. Some breeds that appear to have a greater risk of developing hypoadrenocorticism are Portuguese water dogs, poodles, Rottweilers, Great Danes, West Highland white terriers, and Wheaton terriers. The dog may have a poor response to stress, episodes of gastroenteritis that come and go, or a fulminant gastroenteritis that leads to collapse (a hypoadrenocortical crisis), as well as a loss of body conditioning. Other signs include lack of appetite, increased drinking and urination, dehydration, hyperpigmentation of the skin, depression, vomiting, diarrhea, abdominal pain, and/or weakness. Laboratory diagnosis reveals increased potassium and calcium levels, low levels of glucose and sodium, azotemia, anemia, eosinophilia, and lymphocytosis. An ACTH stimulation test will help to de initively diagnosis Addison’s disease. Review Video: Addison's Disease Visit mometrix.com/academy and enter code: 813552 Megaesophagus Megaesophagus, or dilation of the esophagus, can be either a congenital problem or can be acquired later in life. Animals may be born with esophageal diverticula or with vascular ring anomalies or the dilated esophagus may be idiopathic. In adult animals, megaesophagus may have an idiopathic cause or it can develop secondary to other diseases. The diseases that can cause megaesophagus include esophageal lesions, nervous system disorders, myasthenia gravis, polymyositis, hypoadrenocorticism, systemic lupus erythematosus, dysautonomia, hypothyroidism, or lead poisoning. The primary sign of megaesophagus is regurgitation. Puppies with the disorder will typically be smaller than littermates and begin to regurgitate as soon as they begin to eat solid food. Adult animals also regurgitate and start to lose weight. Both adults and puppies will have respiratory problems due to aspiration of food. Hemangiosarcoma Canine hemangiosarcoma is a very malignant tumor originating in the endothelial cells. Dogs are more likely to suffer from this condition than other animal species, and large breed dogs, particularly Golden retrievers and German shepherds, over the age of 10 years are more likely to succumb to the disease. It is not known what the inciting cause of hemangiosarcoma is in the dog, 100 although chronic ultraviolet irradiation is a risk factor for super icial dermal hemangiosarcoma in certain breeds, such as short-haired lightly pigmented dogs. While the prognosis for hemangiosarcoma is grim, standard therapy for canine hemangiosarcoma involves surgery to remove or debulk the tumor, chemotherapy with doxorubicin (with or without use of cyclophosphamide or vincristine), and radiation therapy. Tracheal Collapse Dogs that suffer from tracheal collapse quite frequently also have chronic bronchitis. For a dog to be diagnosed with chronic bronchitis, it must have a chronic cough lasting at least two months that is not caused by some other anomaly or infection. When a dog has a collapsing trachea, it has an excessive instability of the trachea, which may also be paired with collapse of the large bronchi. A dog suffering from tracheal collapse will give a characteristic “goose honk” cough when the trachea is palpated, when there is pressure from pulling on a lead and collar, or when the trachea collapses in on itself. This problem is more frequently reported in small breeds that are middle-aged or older. Diagnosis of tracheal collapse begins with history-taking that reveals a long- term chronic cough made worse by pressure around the trachea. The physical exam should pay particular attention to the cardiopulmonary system. Other conditions such as congestive heart failure, tumors, primary lung disease, or infections can also cause long-term coughing in dogs. Because Cushing syndrome is found quite frequently in dogs with the same history, it may need to be ruled out as well. X-rays of the chest are helpful in the diagnosis. Many dogs with chronic bronchitis have an increased bronchial pattern. When a dog with tracheal collapse is radiographed, cervical tracheal collapse can be seen during inspiration, while x-rays during expiration can expose an intrathoracic tracheal collapse. Bronchoscopy can be used to visualize the trachea and bronchi and to collect samples for cytology and culturing. Exocrine Pancreatic Insuf iciency Exocrine pancreatic insuf iciency is a disease in which there is loss of pancreatic function. This can occur due to chronic pancreatitis, idiopathic atrophy of the pancreatic acinar cells, and very rarely, pancreatic duct obstruction or tumor formation. The damage to the pancreas causes loss of lipase, trypsin, and amylase production and decreases production of bicarbonate, which aids in absorption of Vitamin B 12; this leads to malabsorption of nutrients. Signs of pancreatic insuf iciency include large-volume gray or yellow cow-patty-like diarrhea that occurs frequently throughout the day. The dog often produces gas, has episodes of diarrhea, loses weight, has a ravenous appetite, and may become 101 cachexic. Other signs may include unthrifty hair coat, pica, and coprophagia. This condition appears to be hereditary in German shepherds. Exocrine pancreatic insuf iciency is caused by loss of pancreatic function that leads to maldigestion and associated digestive disturbances. Diagnosis is based upon history, clinical signs, including frequent loose stools, diarrhea, weight loss, and muscle mass loss, and serum blood testing. Routine blood and chemistry testing usually are normal. If the animal does have high blood and urine glucose with signs of exocrine pancreatic insuf iciency, concurrent diabetes mellitus should be considered. Some dogs have decreased levels of Vitamin B12 (cobalamin) and/or Vitamins A and E. To de initively diagnose exocrine pancreatic insuf iciency, a serum sample should be taken after the animal has fasted to determine the concentration of trypsin-like immunoreactivity. Trypsin is considered to originate only in the pancreas and is an indicator of pancreatic problems; in cases of exocrine pancreatic insuf iciency, trypsin concentration will be low. Chronic Small Bowel Diarrhea The differential diagnosis of a dog with chronic small bowel diarrhea consists of ive broad categories: small intestinal disease, dietary issues, metabolic disturbances, infectious diseases of the gastrointestinal tract, and exocrine pancreatic insuf iciency. Small intestinal disease can be caused by bacterial overgrowth secondary to loss of normal lora due to drugs or toxins or idiopathic causes. Motility disorders such as increased transit time can cause diarrhea. Tumors, in lammation, obstructions, congenital abnormalities, and lymphangiectasia of the small intestine can interfere with absorption and secretion. Dietary intolerances or food allergy can cause a dog to have diarrhea. Diseases that damage the liver or kidneys or hypoadrenocorticism can cause small intestinal diarrhea. Infections with parasites (Histoplasmosis or Giardia), bacteria (Salmonella), or mycobacteria can lead to diarrhea originating in the small intestine. Another cause of small bowel diarrhea in the dog is exocrine pancreatic insuf iciency. Aortic Stenosis The dog can suffer from three types of aortic stenosis: valvular aortic stenosis, supravalvular aortic stenosis, and subaortic or subvalvular aortic stenosis. Of these three, the most commonly encountered type is subaortic stenosis. Regardless of type of stenosis, the obstruction causes increased stress on the ventricular wall. This affects left ventricular emptying, leading to left ventricular hypertrophy in an attempt to normalize ventricular systolic function. Hypertrophy then creates the potential for ischemic areas to form on the myocardium, resulting in mitral regurgitation and the development of 102 ventricular arrhythmias. Some dog breeds that are predisposed to aortic stenosis are large breed dogs such as the Newfoundland, the Boxer, the Rottweiler, the German shepherd, and the Golden Retriever. Heartworm Clinical signs in a dog with heartworm infection depend on worm burden, how long the animal has had the infection, how the immune system reacts to the presence of live and dead worms, and the amount and type of damage caused by the infection. Some dogs have no symptoms; other dogs develop signs such as exercise intolerance, coughing, dif iculty breathing, epistaxis, lethargy, and ascites. The dog may develop increased lung sounds and heart murmur. Chest x-rays may reveal heart and pulmonary artery enlargement and lung densities. The animal may be anemic, have eosinophilia, basophilia, or hyperglobulinemia, and have protein spill over into the urine. De initive testing is done via antigen detection; the antigen is generally detected six to seven months post-exposure. Ehrlichiosis Canine ehrlichiosis is caused by the rickettsia, Ehrlichia canis , which infects the monocytes and lymphocytes. The disease can either be acute or chronic and can cause a number of signs. It is spread by the brown dog tick Rhipicephalus sanguineus. Clinical signs include a recurrent fever, anemia, subcutaneous hemorrhages, bleeding from the nasal passages, thick nasal discharge, loss of weight, lymphadenopathy, swollen spleen, arthritis in multiple joints, central nervous system disturbances, and/or paralysis. The disease is diagnosed by clinical signs and laboratory testing by serum antibody testing and buffy coat and regular smears. The dog may also have neutropenia, non-regenerative anemia, thrombocytopenia, and hyperglobulinemia. Treatment is best accomplished through the administration of tetracycline, oxytetracycline, and doxycycline. Herpesvirus 1 Infection Canine herpesvirus 1 is a virus carried by many dogs but can cause a fatal sickness in neonatal puppies less than one month of age. The virus attacks the puppies either in utero or shortly after birth and damages the liver, kidney, lungs, and other body tissues. The clinical signs of infection in the puppy include green feces, refusal to feed, belly pain, dif iculty breathing, and possibly death. In adult dogs, the clinical signs include mild nasal discharge and in lammation of the conjunctiva. Occasionally, there will be signs of a reproduction infection (discharge, blister-like lesions on the genitalia, and infertility). Diagnosis is based upon clinical signs and virus isolation/antibody staining of affected tissues. The only treatment is supportive care. 103 In luenza An illness that is only recently emerging is canine in luenza. It is caused by the in luenza A virus (possibly from an equine strain) and is highly contagious; airborne or fomites spread the disease. Canine in luenza was irst discovered in Florida greyhounds in 2004 and has now spread to institutions such as boarding kennels, veterinary clinics, and animal shelters. Elderly dogs and puppies seem to be more susceptible to the disease, which causes signs such as coughing, fever, nasal discharge, loss of appetite, lethargy, and dif iculty breathing. Most dogs present with a mild disease that runs its course in one to three weeks. Occasionally, pneumonia due to bacterial infection complicates the disease process. Treatment is primarily supportive care, although antibiotics should be used in cases of secondary bacterial infection. Leptospirosis Canine leptospirosis is caused by various Leptospira types: interrogans (serovars icterohaemorrhagiae and canicola ), grippotyphosa , pomona , and bratislava. The disease has a wide range of signs, with some infected dogs appearing perfectly healthy and others having a fulminant acute disease course. The disease is transmitted by dogs carrying Leptospira canicola or by rodents (mice and rats) that carry Leptospira icterohaemorrhagiae. The acute disease is caused by the spirochetes attacking various body organs: the liver, kidney, spleen, and lymph nodes. The dog will start to vomit, refuse food, and have a fever. Liver and spleen damage may cause icterus and kidney damage renal failure, which is the most severe sign of infection. The gastrointestinal tract can be damaged as well, leading to continued vomiting and bloody stools. Treatment is good nursing care along with antibiotics, such as penicillin G, erythromycin, streptomycin, ampicillin, or chloramphenicol. Lyme Disease Lyme disease (or Borreliosis) is a disease caused by the spirochete Borrelia burgdorferi. It is spread by the Ixodes dammini tick, which becomes infected while feeding on infected small mammals. The organism causes a number of syndromes such as kidney problems, cardiac abnormalities, neurological disorders, and joint and limb disease. The most common clinical signs exhibited by the dog are fever, lameness, painful and swollen joints, loss of appetite, depression, and swollen lymph nodes. Renal disease is the second most common manifestation of Lyme disease and usually leads to death. Diagnosis is based upon clinical signs and laboratory testing. Treatment consists of a 10- to 14-day course of doxycycline or amoxicillin. Prevention includes adequate control of the tick vector and vaccination. 104  Review Video: Lyme Disease Visit mometrix.com/academy and enter code: 505529 Nocardia Asteroides Nocardiosis is a disease caused by a gram-positive, aerobic bacterium Nocardia asteroides. The organism is found in the soil, enters the body through wounds or by inhalation, and causes a chronic disease of cats and dogs along with other animals. Dogs are prone to develop a thoracopulmonary disease characterized by loss of appetite, weight loss, and fever. As the disease progresses, the animal may develop pleuritis or peritonitis along with abscess formation in the brain, heart, liver, and kidneys. Another form the infection takes is the mycetoma or skin form. After infection through a wound, a lump forms that will rupture and weep luid. More areas of infection form and may eventually coalesce into draining sinuses. Along with these lesions, the animal may have a fever, be depressed, refuse to eat, and lose weight. Cherry Eye Cherry eye is caused by the prolapse of the gland associated with the third eyelid. In a normal dog, this gland is anchored to the periorbita beneath the third eyelid. Some breeds of dogs have a weak attachment, which predisposes them to a prolapse. Younger dogs are also usually af licted with this condition. Breeds prone to developing cherry eye include the beagle, bulldog, bloodhound, cocker spaniel, Lhasa apso, and Shih Tzu. The condition can occur in just one eye or both eyes can be affected. The prolapse resembles an oval red mass protruding out from under the third eyelid. Irritation of the mass will lead to tearing, reddened conjunctiva, and eye spasms. Gastric Dilation and Volvulus Gastric dilation and volvulus is a syndrome that occurs in dogs that is frequently associated with large meal ingestion. The stomach ills with gas and twists around its axis, making it impossible for gas or food to exit the stomach. The stomach itself can be damaged due to local ischemia, compromised blood supply, or rupture of the stomach wall if pressure becomes too great. Other organs can be affected as well. The twisting of the stomach may squeeze the portal vein and caudal vena cava, obstructing blood low from the abdomen to the heart. The expanding stomach can also press on the diaphragm, leading to breathing dif iculty. These factors make gastric dilatation and volvulus syndrome an emergency that may lead to shock and cardiovascular failure. The cause of gastric dilation and volvulus syndrome is not entirely understood. Some factors that predispose a dog to developing the syndrome include the 105 breed of the dog. Large deep-chested breeds are more susceptible to develop the syndrome, such as the Great Dane, Weimaraner, St. Bernard, Irish setter, Gordon setter, or Golden retriever. Other factors may include feeding one large meal a day, older age, intense activity and stress, or previous splenectomy. Signs that a dog may be suffering from gastric dilation and volvulus syndrome include unproductive retching, a distended abdomen, drooling, increased heart and breathing rates, anxious appearance, refusal to lie down, and signs of shock, such as weak pulse, pale mucous membranes, and slow capillary re ill time. Gastric dilation and volvulus syndrome is diagnosed based upon the clinical signs at presentation and radiographs. A right lateral abdominal radiograph of a dog with a gastric dilation and volvulus will reveal a distended gas- illed stomach that occupies most of the abdomen. The stomach may also appear as a double bubble, and may actually appear compartmentalized due to the twisting of the stomach around the central axis. Other testing is usually postponed during the acute phase, but blood testing will reveal an acute in lammation, along with electrolyte abnormalities and acid/basic disturbances. Other disease conditions that mimic gastric dilation and volvulus syndrome include abdominal foreign bodies, torsion of the spleen or mesentery, hernias, or abdominal neoplasia. Mammary System Tumors The female dog has ive mammary glands running in two separate rows from the thorax to the inguinal region. These run from the thorax to the inguinal area, or cranial glands, and caudal thoracic, cranial, and caudal abdominal and inguinal mammary glands. More than half the tumors in female dogs are mammary tumors and about half of these are malignant. Tumors are more common in female dogs over eight years of age, and most tumors start in the two most caudal sets of mammary glands. If a female dog is spayed before her second estrus, it will reduce the chance of acquiring mammary tumors to less than ten percent; spaying before the irst estrus will reduce the risk to.05 percent because mammary tumors are in luenced by estrogen and progesterone. Elbow Dysplasia Elbow dysplasia is a general term that means elbow joint arthritis associated with developmental causes. There are four types of elbow dysplasia: ununited anconeal process, osteochondritis dissecans, fragmented coronoid process, and elbow incongruity. These diseases can occur separately or in any combination. Dysplasia is frequently common in both elbows; it is an inherited disease and is found in young dogs four to 18 months of age. Large and giant breed dogs are predisposed to developing elbow dysplasia. The breeds frequently represented 106 include Rottweiler, Newfoundland, German shepherd, Labrador retriever, Golden retrievers, Chow, bearded collie, and Bernese mountain dog. Other risk factors for developing elbow dysplasia include feeding a high calorie diet to dogs predisposed to the disorder or rapid weight and growth. Osteochondritis dissecans (OCD) occurs when a piece of cartilage forms a lap or becomes fully detached from the bone; it affects the distal humerus at the medial trochlear ridge. An ununited anconeal process occurs when a bone fragment of the anconeus process fails to unite with the ulna (olecranon) during the irst ive months of life. A fragmented medial coronoid process occurs when a bone fractures or issures off the ulna (the medial coronoid process). An elbow is considered to be incongruent when the elbow joint is malaligned and malformed. This predisposes the affected animal to abnormal cartilage wear and unnatural mechanical forces on the elbow joint. All these conditions lead to pain and arthritic changes in the elbow joint. Hip Dysplasia Canine hip dysplasia is a developmental disease of the hips initially manifesting as joint laxity in the young dog and progressing to malformation and degeneration of the coxofemoral joints, which may lead to degenerative joint disease (osteoarthritis) in the older dog. It is one of the most common skeletal disorders in the dog and tends to occur in large breed dogs, such as Labrador retrievers, German shepherds, Rottweilers, St. Bernards, and Golden retrievers. It has a strong genetic component and can also be in luenced by other factors, including diet (energy and calcium levels), rapid weight gain, and by the pelvic muscle mass. The hip joint laxity can lead to subluxation of the femoral head and the acetabulum. A dog with hip dysplasia has a history of dif iculty rising from a sitting or prone position, has reduced its exercise, seems reluctant to climb stairs or jump, may display a “bunny-hopping” gait, and may have hind limb lameness that gets progressively worse. Physical examination reveals pain when the hip joint is manipulated, laxity of the hip joint, or “Ortolani sign,” which indicates joint laxity but is not diagnostic of hip dysplasia by itself), crepitus of the hip joint, and atrophy of the hind leg muscles. Radiographs (ventrodorsal with the hips extended) are used to assist in diagnosing hip dysplasia. Early hip dysplasia reveals a subluxation of the hip joint. As the disease progresses, the femur head lattens, the joint space narrows, bone spurs form on the femoral neck and joint capsule, subchondral sclerosis of the acetabulum and femoral head occurs. Urinary Tract Infections 107 The dog’s urinary tract is a common site of infection. Most infections involve the bladder, which normally holds sterile urine. A dog with a urinary tract infection may have the following signs: increased consumption of water, urinating frequently and in small amounts, inability to hold urine, and occasionally, bloody urine. Most cases of cystitis are caused by bacteria ascending up the urethra and into the bladder. It is uncommon for male neutered dogs to have a urinary tract infection caused by an ascending infection. To diagnose a urinary tract infection, a urinalysis test strip can be used or the urine can be cultured to discover what bacterial organism is causing the infection. The most common bacterial cause of urinary tract infection in the dog is E. coli. Seizures It is important to investigate the cause of seizures. Animals can have seizures either due to an event occurring outside the brain or because of a primary brain disorder. Conditions outside the brain that can cause seizures include poisons, hypoglycemia, toxins, or medical conditions. Primary brain dysfunction can be caused by infections, trauma, or neoplasia. It is important to rule out these conditions as the cause of seizures. If none of these conditions exist, then the animal may have epilepsy. A common cause of seizures for animals less than one year of age is a brain infection. Animals older than ive years of age commonly have tumors that cause the seizures. Epilepsy with no known cause is most likely to be diagnosed in dogs between one and ive years of age. Certain breeds of dogs, such as Collies, Cocker Spaniels, Basset Hounds, and Schnauzers, are more prone to developing epilepsy. Review Video: Seizures Visit mometrix.com/academy and enter code: 977061 Hypothyroidism Dogs can be affected by hypothyroidism, which is usually the result of destruction of the thyroid gland. The two conditions that destroy the thyroid gland in the dog are idiopathic atrophy of the thyroid gland and lymphocytic thyroiditis. Lymphocytic thyroiditis is an autoimmune disorder in which the thyroid gland is in iltrated by macrophages, lymphocytes, and plasma cells that destroy the follicles and cause the gland to become ibrotic. Dogs over the age of four years and spayed females are more likely to have the disease. Early clinical signs include weight gain, exercise intolerance, dry skin, shedding, lethargy, and thinning hair. As the condition worsens, the skin may thicken due to deposition of glycosaminoglycans in the dermis; this is most pronounced in the face giving the animal a “tragic” expression. Treatment is with replacement thyroxine (T4) at the dose of.01 to.02 mg/lb daily, divided into two doses. 108 Activities (Veterinary Practice Roles) Data Gathering and Interpretation History, Examination and Environment Equine Passive Stay Apparatus The horse has a passive stay apparatus on both the front and rear legs that allows the horse to stand on its feet for a long amount of time without exerting much muscular effort. The stay apparatus consists of tendons and ligaments that stabilize the horse’s joints in such a manner that it prevents them from lexing. It consists of three parts: interosseus, proximal sesamoid bones, and sesamoidean ligaments. The shoulder joint, the elbow joint, and the carpal joint are all stabilized or prevented from lexing by pressure exerted on various muscles and ligaments. The pastern and fetlock joints, however, are extended and overextended to prevent the fetlock from drooping to the ground. Spinal Cord The spinal cord lies within the spinal canal. The wall of the spinal cord is formed by the vertebra, intervertebral ligaments, and intervertebral discs. The spinal cord is composed of gray matter and white matter. The white matter branches off into roots (ventral and dorsal), which combine to form spinal nerves. The spinal nerves and blood vessels exit the vertebral canal via intervertebral foramina, which are openings between the vertebral arches. The spinal cord itself is covered by three separate membranes. The dura matter lies against the spinal canal. It is composed of two layers: the periosteum (outer layer) and the investing layer. The arachnoid mater is the middle layer and the pia mater is the innermost layer