Guinea Pig Biology, Husbandry, and Diseases PDF

Biology, Husbandry and Diseases of the Guinea Pig Rodent Suborders HYSTRICOMORPHA SCIUROMORPHA MYOMORPHA (porcupine-like) (squirrel-like) (rat & mouse-like) Guinea Pig Squirrel Rat Chinchilla Chipmunk Mouse P...

Biology, Husbandry and Diseases of the Guinea Pig Rodent Suborders HYSTRICOMORPHA SCIUROMORPHA MYOMORPHA (porcupine-like) (squirrel-like) (rat & mouse-like) Guinea Pig Squirrel Rat Chinchilla Chipmunk Mouse Porcupine Beaver Hamster Capybara Gopher Gerbil Porcupine Chinchilla Guinea pig  Cavia porcellus Common names: Guinea Pig Cavy The classification of chinchillas within the Hystricomorpha suborder reflects their evolutionary history and shared anatomical features with other members of this group. American or shorthair Abyssinian Peruvian, Silkie nude Abyssinian (short-haired with rosettes) American (smooth, short-haired) Silkie/Sheltie (smooth, long-haired) Skinny (hairless). Research Uses Immunology Complement and red blood cell donors for diagnostic testing Respiratory anaphylaxis Airway research Dermatology Infectious disease Tuberculosis, typhus, Brucelosis Dunkin Hartley Guinea pigs have a stocky build, large head, short legs, and unfurred, short ears. Head and body length is 200–400 mm, there is no external tail, and weight is 500–1,500 g. They live in groups of up to 10 individuals and inhabit burrows that they or other animals dig. They are most active at night, when they feed a variety of plant materials. Dentition I 1/1, C 0/0, P 1/1, M 3/3 All teeth grow continuously Malocclusion of molars and premolars is common Guinea pigs have a full elodont and hypsodont dentition (i.e., continuously growing and erupting ["open-rooted"] teeth with a long anatomic crown). Malocclusion Usually involves premolars and molars Clinical signs include: Weight loss, excessive salivation, tongue trauma Treatment involves periodic trimming Incisor overgrowth is usually secondary to premolar/molar overgrowth GI Tract Fully glandular stomach Large cecum Guinea pigs produce two types of fecal pellets: nitrogen-rich intended for cecotrophy, and nitrogen-poor delivered as fecal pellets. When food is continually available, ~40% of the feces are reingested, and 90% of this coprophagy occurs at night. When food is limited, guinea pigs ingest feces during parts of the day when food is unavailable. Feet  External genitalia Single pair of inguinal nipples  Extrude penis Normal Parameters Adult body weight: male 900-1200 g female 700-900 g Life span: 3-7 years Rectal temperature: 100.2-103.1oF First estrus: 68 days Estrus cycle: 15-17 days Gestation: 63 days average Fertile: 4-5 years  Lymphocytes are the predominant WBC in guinea pigs and range from 45%–80% of the WBC count. Many small lymphocytes are similar in size to erythrocytes. Large lymphocytes contain Kurloff bodies, large intracytoplasmic mucopolysaccharide inclusion bodies. Pregnant females may have 2%–5% lymphocytes with Kurloff bodies in their peripheral blood; they are present in large numbers in adult females, and numbers fluctuate with the stage of estrous cycle. There are few Kurloff bodies in adult males, and they are rarely seen in newborns. Kurloff Cell Specialized natural killer cell Large mucopolysaccharide intracytoplasmic inclusion Population shifts from lungs and spleen to thymus and placenta during pregnancy Unknown function  Nutrition Requires Vitamin C in the diet. Use commercial diets within 90 days of milling Cabbage and kale are high in vitamin C Vitamin C in water must be changed daily Do not feed antibiotic containing diets Picky eaters Very reluctant to eat new feeds Begin to discriminate between food and nonfood within a few days of birth Introduce experimental feeds early and gradually  Vitamin C Deficiency Scurvy, Scorbutism GP’s are L-gluonolactone oxidase deficient Necessary for conversion of glucose to ascorbic acid Causes defective formation of collagen, osteoid, dentin Clinical signs: Swollen, painful joints Reluctance to move Delayed wound healing Hemorrhages Impaired bone/teeth formation Death Vitamin C Deficiency Histology Disruption of epiphyseal cartilage and new bone spicules Bone marrow fibrosis  Vitamin C Deficiency Prevention Sources of Vitamin C Daily vitamin C source 10 mg/kg Cabbage or kale 30 mg/kg – pregnant sows Oranges or green pepper Ascorbic acid in water 200-400 mg/l Treatment Prepare daily > 50 mg/kg daily Injection vs. oral Continue until improvement is seen Metastatic Calcification Common in pigs over one year Usually incidental necropsy finding Typically no clinical signs +/- muscle stiffness +- renal malfunction Widespread tissue mineralization Kidney, stomach, heart Liver, uterus, colon, etc. Possible diet connection Can induce by feeding: Excessive phosphorus or Excessive calcium Foods to Avoid Avocado: All parts of the avocado plant are toxic to guinea pigs. Allium vegetables: Onions, garlic, leeks, chives. Animal protein: Meat, poultry, fish, eggs, dairy products. Processed foods: Bread, pasta, chips, crackers, butter: Can cause digestive issues. Raw potatoes: Contain solanine, which is toxic. Hot peppers: Can irritate their digestive system. Certain parts of tomatoes: Unripe tomatoes, leaves, and stems contain tomatine, which is toxic. Husbandry Guinea pigs are nervous animals and may refuse to drink or eat for a period after any significant change in their location, feed, or husbandry. The effect of environmental changes on guinea pigs is minimal or nonexistent when two animals are kept together. Guinea pigs live in family units centered on an alpha male. Mature males, and especially strangers, will fight. However, two males raised together from a young age or a group of nonbreeding females do not develop dominance problems. Social problems are diminished with castration and ovariohysterectomy, but learned behavior in adult males after castration may still make them antisocial. Behaviors Freeze Reaction Tonic immobility following noise, shock or environmental change May last 20 minutes Scatter Reaction Scatter in all directions, stampeding, running in circles, trampling young Response to sudden movement or noise Preyer or Pinna Reflex Cocking of ear in response to sharp sound Absence means hearing dysfunction Used in otologic research  Guinea pigs are neophobic, ie, afraid of new things, especially with regard to food and water. Any changes in appearance, taste, texture, etc, can put guinea pigs off feed or water. Guinea pigs develop food preferences early in life and may not recognize new food items as food if introduced later. This is why it is important to expose young guinea pigs to a variety of foods, especially a variety of vegetables, early in life. Breeding First breeding: 2-4 months Estrus cycle: 15-17 days Breeding life: 18-20 months Mating Courtship by boar Sniffing, circling, licking, nibbling, mounting Lordosis by sow 75-80% of matings are fertile  Dystocia Causes: Incomplete relaxation of pubic symphysis Large or malformed fetus Abnormal presentation Uterine inertia Pregnancy toxemia Therapy Oxytocin if pubic symphysis is separated C-section Prevention First breed sows prior to 6 months of age Avoid obesity  Pregnancy Toxemia Occurrence Last 2 weeks of gestation / within days of parturition Pregnancy is not an essential factor Predisposing factors Obesity and fasting 1st or 2nd pregnancy Diet change Nonspecific stress Known causes Uteroplacental ischemia Aortic compression caudal to renal arteries Placental degeneration and DIC Fasting (anorexia) resulting in ketosis Pregnancy Toxemia Lesions Hemorrhage and necrosis at placental sites * Fatty changes in liver * Adrenal gland enlargement with hemorrhage Necrosis of renal proximal tubules Proteinuria Prevention is much more successful than treatment Mothering Sows are not attentive mothers Neonates must nurse “on the run” If not nursed for 24 hours, sows may not return to nursing Preweanings will nurse from different sows and strip milk needed for younger animals. Young Precocious young Walking, eyes open, teeth Wean at 3-4 weeks  Partial Alopecia Sows Late gestation – common Resolves following parturition Weanlings Moth-eaten appearance Guard hairs are emerging and undercoat is thinning Barbering Dominance behavior in groups Self-barbering due to stress  Caging Solid bottom with bedding Wide slotted floors are OK Caging GP’s are messy Will defecate in food and water crocks Recommend Water bottles and J-feeders  Housing Animals weighing up to 350 grams require 20*20 cm² of floor space per animal Animals weighing more than 350 grams must have at least 30*25 cm² Nursing females with their litters also require a minimum of 700 square cm. The minimum height for cages for all sizes of guinea pigs is 17 cm. Unweaned guinea pigs should not be housed with adult animals other than their own parents Caging Pododermatitis Causal factors: Obesity Rough wire flooring Poor husbandry Trauma predisposes to secondary bacterial infections Move to solid, clean environment Local treatment Crusty, painful lesions are slow to heal What could cause this lesion? Cage Trauma Young guinea pigs Wire mesh floors Trapped foot plus excitable animal Flesh wounds and/or fractures Handling Injections  Physical Examination Guinea pigs are easy to hold and restrain. Although they do not bite, very young guinea pigs may nip. Healthy guinea pigs feel “dense” and are alert. Fatigue, lack of interest in surroundings, and light body weight are often general signs of illness. Sick guinea pigs may show evidence of weight loss, hunched posture, abnormal gait, drawn-in abdomen, scruffy fur, or labored breathing. Respiratory and GI conditions are most commonly encountered; thus, ocular or nasal discharges or diarrhea may be present. Feet should be examined for sores or broken nails. Teeth may sometimes overgrow and should be checked. However, the mouth is small, and examination of the oral cavity is difficult A nasal speculum attached to an otoscope handle is an invaluable tool for examination of the cheek teeth in an awake guinea pig. Ears and eyes should be examined for discharges or inflammation, and the submandibular area should be examined for swellings. Oral speculum which is inserted between the incisors to open the mouth. Cheek dilators come in two sizes. The spatulated parts are inserted into the mouth and the spring action spreads the cheeks apart, which allows visual access of the premolars and molars.  Incisor Malocclusion Incisor malocclusion due to a discrepancy in jaw length is uncommon in rodents. A total lack of dietary material for gnawing may result in incisor overgrowth in rodents. Incisor overgrowth may occur subsequent to loss or fracture of an opposing incisor, possibly resulting from a fall or being dropped. Incisor malocclusion may also be secondary to premolar-molar malocclusion. Incisor malocclusion without premolar-molar abnormalities may be relatively rare, Therefore, patients with incisor malocclusion should always receive a comprehensive oral examination. Therapeutic options for incisor malocclusion include: Tooth-height reduction every 3 to 6 weeks or as needed, with appropriate dietary adjustment Extraction of the involved teeth  Caries Caries is a tooth destructive demineralizing process that is initiated by acidic bacterial waste products. It is associated with accumulation of dental plaque on tooth surfaces and the availability of easily digested carbohydrates, such as starch and sugars. Caries lesions in rodents who have brachyodont cheek teeth are similar to the lesions that are seen in humans. When lesions are extensive or symptomatic in anelodont teeth, extraction is indicated. When elodont teeth are affected (eg, guinea pigs, chinchillas), coronal reduction, occlusal correction, and provision of a more natural diet may be effective in controlling the problem if the teeth are still erupting and functional. Guinea pigs are unable to metabolize their own vitamin C, and, therefore, suffer from scurvy if they are fed a deficient diet. Scurvy manifests itself by periodontal disease, gingival hemorrhages, and loosening of teeth. Treatment and prevention consist of feeding fruits and vegetables that are rich in Vitamin C. If the patient is debilitated, tube feeding, fluids, antibiotics, and vitamin supplements may be required Excessive selenium intake interferes with the metabolism of collagen in a similar manner to Vitamin C deficiency, and causes weakening of the periodontal ligament fibers, and, ultimately, tooth instability and eruption problems. Correcting the diet is usually curative, if the problem is recognized before significant secondary changes occur.  Anesthesia A preanesthetic evaluation is indicated for all dental procedures requiring general anesthesia. The small size of most rodents necessitates a different approach which includes the following: (1) Minimization of stress because it affects their anesthetic responses. It can result in ketosis in guinea pigs. (2) The patient is susceptible to hypoglycemia. If a procedure is anticipated to last for longer than 30 minutes, supplemental 5% concentration of dextrose should be mixed with fluids and injected intravenously, intraperitoneally. Rats, gerbils, mice, hamsters, guinea pigs, and chinchillas do not vomit, which obviates preanesthetic fasting. Care is necessary, however, as pressure on the abdomen can result in regurgitation, particularly in guinea pigs. Guinea pigs and chinchillas often retain food in their oral cavity or pharynx. The risk of aspiration in these species can be reduced by a short period of fasting before anesthesia, but, conversely, prolonged food deprivation must be avoided because it induces hepatic dysfunction. Heated surgical surfaces, hot water bags, or bubble wraps are mandatory to control heat loss. Hypovolemia is often overlooked in a small patient and should be controlled by injecting saline solution at a rate 5- 10mL/kg/h. Salivary and respiratory secretions always interfere with dentistry and are decreased by using anticholinergics. Secretions are particularly thick in guinea pigs so atropine should be given SC at a dose of 0.05 mg/kg. For dental surgery, opioids followed by nonsteroidal anti-inflammatory drugs (NSAIDs) are recommended.. Combination of parenteral sedation and inhalation anesthesia is preferred. Midazolam is the preferred benzodiazepine because it is water soluble and therefore less irritating when administered (1 - 2 mg/kg IM or SC for sedation). Anesthesia can then be induced and maintained with isoflurane inhalation anesthesia. Alternatively, anesthesia can be induced with a dissociative anesthetic such as ketamine in combination with an a-adrenergic agonist such as xylazine. Induction with agents that have a high risk of apnea, such as propofol and thiopental, is discouraged Ketamine 50 mg/kg with 5 mg/kg xylazine in hamsters provide 30 minutes of anaesthesia. Ketamine at 40 mg/kg in conjunction with xylazine at 5 mg/kg can be used in guinea pigs to produce a light plane of anaesthesia. Ketamine at 40 mg/kg may also be used with medetomidine at 0.5 mg/kg for guinea pigs. Isoflurane Induction levels vary at 2.5–4% and maintenance usually is 1.5–2.5% assuming adequate analgesia. Isoflurane is then gradually introduced, first 0.5% for 2 minutes, then, assuming regular breathing, increased to 1% for 2 minutes and so on until anaesthetic levels are reached. For a routine occlusal adjustment, a single dose of an opioid is often sufficient, whereas NSAIDs can be continued for 3 to 5 days. Consideration must be given to the potential adverse effects of NSAIDs, such as GI bleeding and reduced renal blood flow. GI stasis commonly accompanies dental disease and its treatment. GI stasis can be managed with an appropriate diet, hydration, and pain management and prokinetic drugs such as metoclopramide (0.2 to 1 mg/kg PO, SC, or IM q12h) or cisapride (0.1 to 0.5 mg/kg PO q8-12h). Secondary infections must be treated. Facial abscesses are frequently associated with dental disease, but infection of oral ulcers, bacterial rhinitis, dacryocystitis due to apical elongation, and even pneumonia can occur secondary to dental disease. In rabbits, these abscesses have been found to contain both aerobic and anaerobic pathogens, so antimicrobials must be chosen appropriately. Broad-spectrum antibiotics are considered ideal, but choices are limited in many species, especially guinea pigs and hamsters, because of the risk of fatal disruption of normal GI flora.  Venipuncture Peripheral Veins Lateral Saphenous Vein: Located on the lateral aspect of the hind leg, this vein is often the most accessible for small blood draws. The guinea pig should be positioned comfortably to allow for easy access to the hind leg. Use a small gauge needle (e.g., 25-27 gauge) to minimize trauma. Cephalic Vein: Found on the forelimb, the cephalic vein can also be utilized for small blood samples. Proper restraint is crucial to prevent movement during the procedure. Injection / Blood Collection Injection / Blood Collection Blood Collection Genitourinary disease  Urinary Problems Guinea pigs are very prone to development of urinary calculi (stones or uroliths). These stones most often form in the bladder but may also form in the kidneys or ureters. Stones may become lodged in the ureter or the urethra causing a life-threatening obstruction. Urolithiasis is a common problem in older guinea pigs, especially females, because of the proximity of the urethral orifice to the anus and the high risk of infection with fecal contaminants such as E coli. Clinical signs include dysuria, vocalizing when attempting to urinate, and occasionally hematuria. Diagnosis is by abdominal radiology. The calculi are radiopaque and usually composed of calcium carbonate or calcium phosphate; calculi can also be composed of calcium oxalate. Obstructive urolithiasis, hydroureter, hydronephrosis, and possible concurrent septicemia can develop if the problem is not treated. In addition to sex and age, diet may be related to urolithiasis. Foods high in calcium, eg, alfalfa hay, may result in a high dietary calcium:phosphorus ratio. Urinary ascorbate, if present at a high concentration, increases stone formation in guinea pigs given high-calcium or high-oxalate diets. This may be both beneficial and deleterious, ie, needing to give enough vitamin C to prevent scurvy but not increase stone formation. Surgical removal of uroliths is standard treatment. However, it is often complicated by severe inflammatory reactions to suture material. Although uncommon, cystitis occurs more often in female guinea pigs than males, and often stones develop in association with infection. Signs of urinary problems include anorexia, blood in the urine, straining to urinate, a hunched posture (with straining), and small, frequent urinations; if an obstruction occurs, the guinea pig will be unable to produce urine. Sick guinea pigs may require hospitalization and supportive care, including fluid therapy and syringe feeding, as well as surgery.  Ovarian Cysts Cystic rete ovarii have been identified in 76% of female guinea pig most commonly in animals age 2 to 4 years. Cysts develop spontaneously, range in diameter from 0.5 to 7 cm. They may be single or multilocular. In most cases, both ovaries are affected. Affected animals present with abdominal distention anorexia, fatigue, and depression. Bilateral symmetric hair loss can be seen in the flank region. Decline in fertility after 15 months of age is a major sign. Respiratory system disease Bordetella bronchiseptica Gram negative aerobe Epizootic pneumonia with high mortality Sporadic deaths, more often in winter Clinical signs Lethargy Rough hair coat Nasal discharge Sneezing Sudden death Metritis and abortion. Bordetella bronchiseptica Otitis media Torticollis (head tilt) if severe Radiograph Tympanic bulla Bordetella bronchiseptica Bronchopneumonia Consolidated lungs Large accumulations of neutrophils and intraluminal debris  Bordetella bronchiseptica Transmission Direct contact Fomites Aerosol Rabbits are asymptomatic carriers Don’t house rabbits and guinea pigs together Beware of traffic patterns Prevention is more successful than Treatment Antibiotic therapy B bronchiseptica possesses a beta-lactamase and is resistant to many penicillins and cephalosporins and mostly resistant to trimethoprim-sulfamethoxazole. Most isolates are sensitive to doxycycline (2.5–5 mg/kg, PO, twice a day) and fluoroquinolones (marbofloxacin, 4 mg/kg/day, PO; ciprofloxacin, 10–20 mg/kg, PO, twice a day; enrofloxacin, 5–10 mg/kg, PO, twice a day for 14 days).  Cervical Lymphadenitis = Lumps Streptococcus zooepidemicus Clinical signs Suppurative or caseous lymph node abscesses Bronchopneumonia, pyothorax, sepsis – less common Transmission Direct contact or aerosol Treatment Surgical drainage Antibiotics Rabbits and other species Asymptomatic carriers Streptobacillus moniliformis can cause similar lymph node lesions Streptococcus equi subsp zooepidemicus may be carried in the nasopharynx as a latent infection. Abrasions of the oral cavity (eg, molar malocclusion) allow bacteria to be transported to draining lymph nodes of the head and neck, causing suppurative lymphadenitis. Clinically, guinea pigs present with large, unilateral swellings in the neck. The differential diagnosis should always include cavian leukemia. Treatment is surgical excision of the affected lymph nodes and systemic antibiotic treatment. Streptococci are generally sensitive to chloramphenicol (50 mg/kg, PO, twice a day), and azithromycin (15–30 mg/kg/day, PO; discontinue if soft feces result) and fluoroquinolones; however, bacterial resistance to these antibiotics is now frequently seen. Lymphosarcoma = Cavian Leukemia Retrovirus Type C Oncornavirus Virus is widespread Transplacental transmission Dormant until aged or stressed Lymphoblastic cell infiltration Liver, spleen lymph nodes  Streptococcus pneumoniae Epizootic outbreaks with high mortality Transmission Asymptomatic carriers, including GP’s, rats and man Direct contact Stress-induced Fibrinosuppurative lesions Pneumonia Pleuritis Pericarditis Peritonitis Clinical signs of pneumonia are dyspnea, wheezy breathing, sneezing, nasal discharge, and coughing. The affected guinea pig becomes depressed and anorectic. S pneumoniae infections are nearly always associated with middle ear infection and head tilt. Increased radiodensity of the affected tympanic bulla may be seen on radiographs. Because of limited antimicrobial sensitivity, chloramphenicol (50 mg/kg, PO, twice a day) is the recommended treatment. A major differential diagnosis for pneumonia is Bordetella bronchiseptica infection. Chlamydial conjunctivitis is one of the most common causes of infectious conjunctivitis in guinea pigs. It is caused by Chlamydia caviae, an obligate intracellular bacterium. Clinical disease usually is found in young animals 4–8 weeks old. Rhinitis, lower respiratory tract disease, and abortion can also occur. The organism infects primarily the mucosal epithelium of the conjunctiva and, less frequently, the genital tract of guinea pigs. Asymptomatic infection can occur, but clinical disease most often results in mild inflammatory conjunctivitis with a slight, yellow-white discharge, conjunctival hyperemia, chemosis, and even severe conjunctivitis with profuse, purulent ocular exudate. Antichlamydial therapy with doxycycline (5 mg/kg, PO, twice a day for 10 days) is the treatment of choice and usually results in complete recovery.  Pulmonary Neoplasia Bronchogenic pulmonary adenoma is a common tumor found in guinea pigs. In one study, it occurred in approximately 30% of animals older than 3 years. Bacterial and parasitic enteritis Antibiotic-Induced Enterotoxemia Hemorrhagic Typhlitis Overgrowth of enterotoxin-producing enteric bacteria, ex. Clostridium difficile Often follows antibiotic use, dietary changes, or stress Clinical signs: Anorexia Rapid weight loss Dehydration Diarrhea Death  Antibiotic-Induced Enterotoxemia Enlarged cecum, filled with blood and gas Loss of cecal epithelium, with extensive hemorrhage and necrosis of mucosa and submucosa Supportive treatment rarely effective Antibiotics to avoid: Penicillin, erythromycin, lincomycin, streptomycin, bacitracin Antibiotic-associated enterotoxemia is prevented by treating guinea pigs with appropriate antibiotics. Trimethoprim-sulfa (30 mg/kg SC, IM, or PO q12h × 7 days), chloramphenicol (50 mg/kg PO q12h × 7 days), and enrofloxacin (10 mg/kg PO q12h) are effective and safe in guinea pigs. Salmonellosis S. typhimurium and S. enteritidis most common Transmission by contaminated food or water Sporadic outbreaks with high morbidity & mortality Clinical signs: Clinical signs include conjunctivitis, fever, lethargy, anorexia, rough fur, palpable hepatosplenomegaly, cervical lymphadenitis, and abortion in pregnant sows. Mortality is often high in epizootic outbreaks. If animals recover, organisms may be shed intermittently. Diagnosis is accomplished by isolating the organism from blood, ocular secretions, lymph nodes, or spleen. Because of zoonotic considerations and the potential for a carrier state, treatment is not recommended. Salmonellosis Gross findings Fluid and gas filled GI tract Liver and spleen enlargement Histological findings Multifocal necrosis Liver, spleen, lymphatic tissue Control Depopulation Zoonotic Bacterial enteritis Yersinia pseudotuberculosis, Clostridium perfringens, Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes. Like Salmonella, these are contracted through fecal contamination of food. Y. pseudotuberculosis can cause abscesses of the intestine and of regional lymph nodes. E. coli causes wasting, depression, and death in weanlings. Intestines may contain yellow fluid. Antibiotic treatment is based on culture and sensitivity analysis. Supportive therapy is also indicated. Cryptosporidium sp Protozoan – major cause of enteric disease in GP’s Cryptosporidium wrairi Clinical signs Subclinical infections common Lethargy, rough hair coat, weight loss, diarrhea “Greasy coat” appearance Transmission Contaminated food & water fomites  Cryptosporidium sp Colonize anterior ileum Histologic lesions Fusion, atrophy and metaplasia of villous epithelium Eosinophilic infiltration of lamina propria Diagnosis Identify organisms within: Epithelial cells Mucosal scrapings Fresh fecal smears Fecal floats don’t work No effective treatment Zoonotic potential Dermatophytosis Trichophyton mentagrophytes Asymptomatic carriers are common ZOONOTIC For topical therapy, either enilconazole (0.2% at a dilution of 1:70) or miconazole shampoo (with or without chlorhexidine), once or twice weekly, can be used. Systemic therapy is either itraconazole (10 mg/kg/day, PO) or terbinafine (30–40 mg/kg/day, PO) for 4–8 weeks. Lesions may resolve in 2–3 weeks, but antifungal therapy should be continued until two DTM cultures are negative, with a 2-week interval between cultures. Often, dermatophyte infections of the skin require 2–3 months of therapy. Acariasis Primarily 2 mite species infect GP’s Trixacaris caviae – burrowing mite Neck, shoulders, abdomen inner thighs Alopecia, crusting, intense pruritis Self mutilation, debility, death Chirodiscoides caviae - fur mite Few to no clinical signs Acariasis Trixacaris caviae Chirodiscoides caviae The seizures are controlled by diazepam (1–2 mg/kg, IM, as needed). The clinical presumptive diagnosis should be confirmed with several skin scrapings, usually revealing a massive T caviae infestation. Treatment involves ivermectin (0.4–0.5 mg/kg, SC, repeated 2–3 times at intervals of 7–10 days), or spot-on dermal treatment with either selamectin (15 mg/kg for < 800 g body weight; 30 mg/kg for >800 g body weight). The guinea pig should also have a whole body washing with fipronil repeated twice at intervals of 7–10 days. Fipronil should not be used when open skin wounds are present. Lice Chewing lice Occasional alopecia and mild pruritis Spread by direct contact Gyropus ovalis Nits on hair shaft Gliricola porcelliis A single application of 0.05 mL of a topical solution containing 10% imidacloprid and 1% moxidectin is an effective treatment for lice infestations in guinea pigs. Prevention is aimed at improving sanitary conditions in the animal’s environment.  Alopecia (nonpruritic) Sows Late gestation – common Ovarian cysts can cause bilateral symmetric flank alopecia. Resolves following parturition Weanlings Moth-eaten appearance Guard hairs are emerging and undercoat is thinning Barbering Dominance behavior in groups Self-barbering due to stress Lymphocytic Choriomeningitis (LCM) RNA Arenavirus Clinical signs: Asymptomatic Rear limb paralysis CNS disturbances Eradication Colony depopulation