Chapter 12 - Principles & Methods of Disease Control PDF

# Chapter 12 - Principles & Methods of Disease Control ## Lesson 1: Prevention ### Introduction Fresh air and proper nutrition promote optimal health and help prevent disease. Improper management practices predispose animals to infectious diseases. Health management programs include management pra...

# Chapter 12 - Principles & Methods of Disease Control ## Lesson 1: Prevention ### Introduction Fresh air and proper nutrition promote optimal health and help prevent disease. Improper management practices predispose animals to infectious diseases. Health management programs include management practices as preventive measures against disease. Principles for prevention of disease and the utilization of preventive measures foster optimal animal health and welfare; enhance productivity and economic efficiency; and assure abundant, safe, and wholesome food to the consumer. The study and utilization of proper management practices in husbandry, nutrition, and epidemiology of diseases will minimize or totally prevent diseases. Epidemiological management practices are targeted toward sources and transmission of diseases and immunity of animals against diseases. These practices consider the risks of introduction and exposure to diseases and the necessity of immunizing animals. ### Nutritional Management Practices Poor nutrition can predispose animals to disease by not supplying the proper nutrients for optimal health. Some general rules for proper nutritional management include: - Provide sufficient clean water. - Provide adequate protein, carbohydrates, minerals, vitamins, fats, and oils. - Provide adequate forage to horses and ruminants. - Prevent overcrowding and overgrazing of pastures. - Ensure that newborn animals receive enough good quality colostrum during the first 6 hours after birth. ## Lesson 2: Treatment ### Treatment Options A veterinarian makes a diagnosis based on evaluation of clinical signs exhibited by a diseased patient and possibly supported by interpretations of laboratory tests. The veterinarian's understanding of the process of the diagnosed disease determines the treatment regimen. A decision may be that no treatment is necessary, which means the animal can overcome the disease, the disease will run its course, and the animal will recover. If treatment is deemed necessary, the veterinarian may provide one or a combination of the following: - Drug and chemical therapy - Nutritional therapy - Physical therapy - Supportive therapy - Surgical therapy Another important responsibility is the provision for the care, comfort, feeding, and alleviation of pain or suffering of the affected animal. In cases of poor to grave prognosis, the option may be to euthanaize the animal. ### Drug and Chemical Therapy Medical therapy requires a thorough knowledge of mode action, safety, and efficacy of drugs or chemicals. Medical therapy involves the selection and administration of drugs affecting body systems. These drugs can include antibacterial, anti-viral, anti-inflammatory, and antifungal drugs; and antiparasitic, antiseptic, and anti-neoplastic chemicals. The chosen drug or chemical is administered by topical, oral, or parenteral routes. - Oral dose forms include tablets, capsules, boluses, powders, granules, liquids, and pastes. Soluble powders and liquids can be used for medicating drinking water, and powders and granules for medicating feeds. - The parenteral dose form uses an aqueous solution or suspension. The most frequent administration routes of parenteral drug forms are intramuscular (IM), subcutaneous (SQ), and intravenous (IV). Other routes include intraperitoneal (IP), epidural (ED), intradermal (ID), intracardiac (IC), and subconjunctival. Intramammmary (IMM) and intrauterine (IU) are routes chosen for regional or local action. It is important to follow the label instructions for use of specific drugs and chemicals in animals. The label and package insert provide the necessary information regarding: - Animal species for which the compound is approved - The dose - The route - The condition or use for which the compound is approved - The withdrawal time for slaughter - The discard time for milk Read the label. Use of extra label recommendations must only be undertaken with a clear understanding of legal and medical ramifications. - Over-the-counter (OTC) drugs and chemicals can be administered to animals without the supervision of veterinarians. Prescription (Rx) drugs and chemicals are to be administered by, or on the order of, a licensed veterinarian. Veterinarians administer and dispense OTC and Rx drugs and chemicals. All prescription and extra-labeled drugs and chemicals dispensed must bear the veterinarian's label in compliance to laws and regulations of the Food, Drug, and Cosmetic Act and the State Veterinary Practice Act. ### Nutritional Therapy Nutritional or dietary therapy is an integral part of both preventive health care and treatment for diseased and surgical patients. Nutritional therapy can complement, or even replace, drugs and surgery in some cases. The alteration of general diets helps manage a disease process and requires modification of the diet as the clinical condition of the animal changes. Therapy involves providing nutrients through enteral and parenteral means. Enteral nutrition is accomplished by hand, self, or force feeding the animal orally with solid and liquid foods. Parenteral nutrition utilizes sterile nutrient solutions. These solutions are administered under the skin or in the vein, muscle, or peritoneal cavity. ### Physical Therapy Physical therapy complements drugs and surgery in the treatment of musculoskeletal and nervous system diseases. This therapy assists in improving normal function of muscles and nerves and decreases fluid collections. Therapeutic practices such as walking and swimming and applying various forms of massage and vibration are beneficial. Physical therapy is necessary for weak animals unable to self-exercise, particularly those patients recovering from illness or surgery. ### Supportive Therapy Supportive therapy is the attempt to sustain the life of a patient by supporting the physiological functions of body systems. Anemic and/or dehydrated diseased patients need treatment with blood, plasma, and physiological-electrolyte transfusions. These solutions are administered slowly by the drip-method via the intravenous route. Proper restraint and sedation may be necessary to handle animals for transfusions. Results of laboratory tests will reveal the type and level of supportive therapy needed. ### Surgical Therapy Surgical therapy is the correction for non-infectious diseases such as mineral deposits (stones and sand) in the gall bladder, kidney, bladder, and urethra, and hair balls in the stomach and intestines. Amputations (toe, leg, tail, ear) and eye enucleations are examples of surgeries for treatment of diseased tissues. In addition, drainage tubes for fistula tracts, abscesses, and serum pockets require surgical procedures. Other examples include treatment for abscesses, warts, and tumors and the surgical removal of diseased testicles, ovaries, and uterus. ## Lesson 3: Controlling Internal Parasites ### Purpose The purpose of controlling internal parasites is to reduce the population of infective parasite stages in the animal's environment. This reduces the risk of exposure to internal parasites. ### Objective The objective of control measures is to break the life cycles of internal parasites, whether the parasites have a direct life cycle or an indirect life cycle (intermediate host required). To break the life cycles of parasites, management practices try to: 1. improve the nutrition of the animal, 2. improve the sanitation of the animal's environment, and 3. strategically administer drugs to reduce parasite numbers. These practices lower environmental contamination and the infection of intermediate hosts and definitive hosts. ### Nutritional Management Practices Pasture improvement practices not only improve the quality of forages but prevent severe reinfection of parasites. Such practices help to break parasite life cycles and to improve the nutritional condition of grazing animals. ### Environmental Management Practices Management practices to improve the sanitation of the animal's environment break the life cycles of parasites and promote optimal animal health. Proper management practices include reducing manure on the ground; maintaining clean, dry housing; and draining standing water. - Reduce manure in pastures by preventing overcrowding, overgrazing, and by rotating the animals to different pastures. Other practices include use of a tractor grader to remove manure around feeders and waterers, and use of a tractor harrow to scatter manure on pastures. For pets that live in a confinement area, properly dispose of manure daily to maintain sanitary conditions. - Not only will reducing, removing, and scattering manure lower the population of infective stages of parasites, but those practices will reduce the population of intermediate hosts (flies and dung beetles). The animal's environment needs to be clean, dry, and free of standing water. This type of environment also reduces the number of intermediate hosts (mosquitoes, gnats, snails, fleas). - Periodic use of chemicals effective against intermediate hosts (arthropods and snails) supplements sanitary practices. These complementary practices work to break the life cycles of parasites. ### Strategic Drug Administration Antiparasitic drugs are administered to animals not only as a treatment to kill internal parasites and to stop damage caused by parasites, but to strategically control parasites. Strategic administration of drugs reduces environmental contamination and infection of intermediate hosts and definitive hosts. Strategic administration of drugs to control internal parasites does not take the place of, but supplements, management practices to improve sanitation and animal nutrition. - A strategic method requires proper timing. This means that a drug used to treat a parasite must be administered at the right time taking into consideration of the life cycle of the parasite. Therefore, the correct time is not when the animals are confined and accessible, or because it has been a long time since the animals received a drug, or because administrations are spaced evenly (fall and spring, every 6 months). The correct time is when an animal has become infected, the parasite is beginning to reproduce and cause damage, and conditions for transmission are optimal. - A drug administered at the right time breaks the life cycle of the parasite and prevents transmission buildup of the parasite in animals. In small animals, monthly use of drugs to control heartworms is advised. In livestock, the correct time for administration of antiparasitic drugs is normally dependent on the parasite and the development of optimal environmental conditions. Optimal conditions include moderate temperatures, rainfall, and wet grass. Following 3 to 6 weeks of continuous rain when the soil temperature ranges from 55 to 85 °F would be the right time to practice nutritional and environmental management and drug administration against stomach worms in cattle. Four to 6 months after optimal conditions are present, practice control measures against liver flukes in cattle and bloodworms in horses. After one week of optimal conditions, practice control measures against coccidia in calves. - Periodic fecal examinations can help to reveal fluctuations of parasite eggs per gram of feces to aid the timing of drug treatment measures. In pets, the correct timing of drug treatments requires periodic fecal and blood examinations. When results of fecal flotations, direct fecal smears, or blood tests reveal the presence of parasites, the animal should receive an antiparasitic drug. The animals should receive these tests one to six times a year, routinely. ## Lesson 4: Controlling External Parasites ### Introduction Preventive measures against external parasites (arthropods) of animals include chemical and non-chemical management practices. These management practices include breaking the life cycles of external parasites by killing immature and adult stages in the animal's environment, and killing immature and adult stages that infest animals. Therefore, the control of populations of external parasites focuses on reducing the offspring or future generations of the parasite. ### Environmental Management Practices Environmental management practices direct attention toward destroying the breeding sites of parasitic arthropods that lay eggs in the animal's environment. - Stable flies reproduce in decayed stall bedding, hay, horse manure, lawn clippings, and aquatic vegetation; horseflies, deerflies, gnats, and mosquitoes reproduce in or near water; hornflies reproduce in fresh cattle manure; houseflies and blowflies reproduce in decayed garbage and animal carcasses; and fleas and ticks reproduce in animals' bedding and moist, shaded soil. Preventive measures encourage proper sanitation in an animals' environment. Sanitary practices include properly disposing of decayed wood shavings, vegetation, manure, garbage, and dead animals; and providing clean bedding. Routinely dragging pastures to scatter cattle manure encourages drying of the manure, which interferes with the larval development of hornflies. - Proper drainage is another practice of external parasite control that reduces the quantity of standing water and the production of gnats, mosquitoes, horseflies, and deerflies. In addition, periodic insecticide applications on the premises are helpful. - Sprays, fogs, powders, granules, and baits introduce insecticides into the animal's environment to kill immature and adult stages of arthropods, especially fleas and ticks, in an attempt to break the arthropods' life cycles. Environmental chemical control is more effective in controlling fleas and one species of tick than applying insecticides on animals. ### Animal Management Practices Proper stocking rates of animals prevent overcrowding and accumulation of manure and filth. Also, separation of animals reduces transmission of mites and lice. New animals, whether purchased additions or unwanted strays, may be sources of external parasites (such as ear mites, mange mites, lice, ticks, and fleas). Isolate, examine, and treat these animals until they are free of unwanted parasites. - Observe all animals daily to maintain in a good, healthy condition. Healthy animals tend to have fewer external parasites and are better able to withstand parasite effects. Animals infested with mange mites are less likely to develop a mange condition if they are not under stress. Protection from cold weather and maintaining good nutrition during pregnancy and lactation may reduce the chance of developing mange. Some animals are so bothered by mange mites that they do not feed, and are at risk of more severe diseases during inclement weather due to hair loss. - Strategic administration of insecticides (using the right chemical at the right time) on animals assists in the control of external parasites. When necessary, proper use of chemicals can aid in breaking the life cycles of external parasites. Animal chemical control of the parasites that live on animals such as mange mites, ear mites, and lice is necessary because these parasites breed on the animals and not in the environment. Adult heelflies do not infest cattle, but their larval stages do; therefore, insecticide application on cattle is needed to control cattle grubs. Also, an alternative practice to scattering cattle manure in an attempt to break the life cycle of hornflies is the application of an insecticide on cattle to kill adult flies. - Insecticides are applied to animals either by hand-application or self-treatment methods. Hand-application methods include dip, spray, dust, pour-on, spot-on, injection, and oral. Devices used for self-treatment methods are back rubbers, dust bags and tubes, liquid wicks, and impregnated ear tags and neck collars. Self-treatment devices, when properly used, are more efficient at controlling hornflies than hand-application methods. - Approved insecticides are available for use on animals and application around the premises. An insecticide may be approved for both animals and the premises, but normally the application method requires different insecticide concentrations. Usually the label will recommend a lower chemical concentration for insecticide use on animals. Insecticides used to control external parasites are pyrethroids organophosphates, carbamates, formamidines, and macrolides. ## Lesson 5: Veterinary Biological Products ### Introduction Veterinary biological products are vaccines and antibodies that are produced by laboratory techniques using microorganisms, such as bacteria or viruses. Vaccine products can contain attenuated (weakened) or inactivated (killed) organisms or portions of organisms known to cause a particular disease. These products provide antigens, which the body reacts against by producing antibodies and other substances involved in the immune response. Antibodies are found in products such as antiserum, antitoxins, and colostrum. Biological products may be administered to animals before exposure to disease agents to provide protection or after exposure to the disease to treat the disease or minimize shedding of the infectious microorganisms. - The duration of immunity induced by a vaccine varies by organism and vaccine type. This information is generally included on the vaccine label. Some vaccines require only one shot for life-long immunity, whereas others may need to be administered every year or even more often to maintain protection from the disease. - The USDA's Animal and Plant Health Inspection Service (APHIS) regulates all animal biological products imported in the United States or shipped across state lines. In addition, the USDA tests each product for safety and potency. ### Active Immunization When an animal is inoculated orally, intranasally, or systemically with a vaccine, the immunological defenses of the body respond by producing systemic or local antibodies or by activating cell-mediated immunity. If an immune response is stimulated by the vaccine, and the animal is later exposed to the same microorganism, it will respond more rapidly and be less likely to become ill or die. ### Modified Live Vaccine A modified live vaccine is an infectious vaccine that establishes an infection in the vaccinated animal. The ability of an organism to cause disease (its virulence) can be reduced (attenuated) so it is still able to infect and replicate. Some live vaccines may possess the ability to revert to a virulent organism and spread to unvaccinated animals. Avirulent bacteria can be produced by culture under abnormal conditions, and viruses can be weakened by growth in abnormal hosts and tissue cell cultures. Rabbits, chicken eggs, and rodent kidney cells are commonly used as culture tissue in the process of modifying live vaccines. Viruses and bacteria are also attenuated using a genetic engineering process. These vaccines are produced using recombinant DNA techniques, by which the genes for virulence are deleted from the microorganisms. ### Killed Vaccine Inactivation of viruses and bacteria used in vaccines is accomplished by destroying its ability to cause disease (its pathogenicity, including infectivity and virulence) while leaving its ability to cause an immune response (its antigenicity) intact. Chemicals or heat are commonly used in the killing process. Examples of compounds used are alcohol, formaldehyde, acetone, and ethylenes. Killed vaccines are unable to infect and replicate. They are usually much safer than live vaccines but may be weaker in antigenicity. A vaccine containing killed bacteria is called a bacterin. - Adjuvants are added to the inactivated vaccines to increase the likelihood of an effective immune response. Antigen-adjuvant mixtures form tissue deposits at the injection site of subcutaneous administrations that are observed as knots in the skin. Also, injection site lesions in the muscle may be related to intramuscular injections of vaccines containing an adjuvant. - A killed vaccine is a noninfectious vaccine. Generally, to be effective, two doses at 3 to 6 week intervals are necessary. The first vaccination is a priming, sensitizing dose which may provide no protection or low protection for a short period of time. The second vaccination is required for effective immunity for a longer duration. ### Subunit Vaccine Purified antigens are produced by filtering immunogenic portions of organisms, such as their waste products, capsules, or isolating genetic material using recombinant DNA techniques. A vaccine containing inactivated toxins (waste products) is called a toxoid. A subunit vaccine is neither a killed vaccine nor a modified live vaccine. The immunization procedure for use of a subunit vaccine is the same as that for using a killed vaccine in animals. ### Passive Immunization The transfer of antibodies to susceptible animals confers immediate passive immunity. The passive immunity is expected to minimize infection and shedding of disease agents and to prevent development of sickness and death. Laboratory production of antibodies is accomplished by active immunization of an animal or through the use of cell lines (hybridomas). - Serum collected from immunized animals contains antibodies. The serum, termed antiserum or antitoxin, is administered subcutaneously to provide systemic protection for 2 to 6 weeks. Monoclonal antibody preparations administered orally provide temporary local immunity. - Colostrum, the first milk produced by female animals that have recently given birth that were actively immunized in the late stage of pregnancy, contains maternal antibodies for the nursing offspring. Newborn animals receive long-standing systemic immunity by nursing adequate amounts of the colostrum during the first 24 hours of life and temporary local immunity by nursing the first 72 hours of life. Commercial colostral antibody products are also available, although they may be less effective than colostrum itself. - The duration of systemic protection provided by colostral immunity is 2 to 12 weeks depending on the quantity and quality of colostrum consumed, the disease, and the level of exposure. As passive immunity decreases, young animals are actively immunized by use of vaccines. Maternal antibodies interfere with active immunity by affecting efficacy of administered vaccines. The exact time of colostral immunity loss cannot be predicted. Therefore, to ensure successful active immunization, young animals must be vaccinated more than once. ### Handling Vaccines Many vaccines should be refrigerated; information about how to store and handle vaccines is on the product label. Do not expose the vaccine to direct or indirect sunlight for any extended period of time. Sanitary measures help to ensure the vaccine is free of blood, feces, hair, and dirt. When handling a live vaccine, do not use chemicals for disinfection of syringes, needles, skin, or vaccine vials. Unused portions of a vial of vaccine must be properly discarded and not stored for later use. - Follow label direction for proper procedures in administering a vaccine. Use the correct dose and route. Do not administer an expired vaccine. Adhere to the withdrawal time for slaughter published on the label. ## Lesson 6: Disinfectants ### Introduction Disinfectants are chemical compounds applied to inanimate surfaces to reduce or eliminate pathogenic microorganisms. Ideal disinfectants have germicidal activity that is potent and broad-spectrum. Disinfection is the act or process of destroying pathogenic organisms. Inanimate surfaces that may become contaminated with bacteria, viruses, and fungi include examination, treatment, and surgery table tops, feeding and watering utensils, cages and stalls, clinic floors, and dirt or concrete flooring of stalls, pens, and lots. - Organic matter, such as manure and soil, commonly inactivates disinfectants rendering the chemicals ineffective. Therefore, disinfectants are more effective when applied to cleaned, hard surfaces than when applied to the ground. ### Classes of Disinfectants - **Alkalies** are compounds that have a high pH (basic) and therefore, a high concentration of hydroxyl ions in solution. Examples of alkalies are sodium hydroxide (lye), lime, soda, and potash. A 2% solution of lye is used for disinfection of soil and rubber boots. Calcium oxide (unslaked lime) powder is applied to contaminated soils. Since alkalies are irritating to animals' skin, the animals should be removed from the grounds before disinfection. - **Chlorine** is a compound that is an effective bleaching agent as well as a disinfectant. Chlorine acts as a disinfectant because of the high concentration of chloride ions in solution. A solution of sodium hypochlorite (household bleach) at a concentration of 0.05% to 0.2% acts as a disinfectant. Bleach degrades when exposed to light and has an offensive odor. - **Formaldehyde** is a gas like chlorine. In solution formaldehyde is called formalin. The commercial concentration of formalin is 40% and has to be diluted with water for disinfection purposes. A 5% formalin solution is a disinfectant and used to disinfect rubber boots, feeding and watering utensils. The odor of formalin is offensive. - **Quaternary Ammonium** is an effective disinfectant when applied to clean, hard surfaces. Solutions of 1:1000 to 1:5000 have acceptable odors and are non-irritating. Because organic matter will inactivate this compound, this class of chemical is commonly used by veterinarians to disinfect cages, utensils, boots, table tops, and flooring (concrete, tile, vinyl). - **Phenol** is called cresol when used as a disinfectant. The effectiveness of a 2% solution of cresol in hot water is fair for the ground and good for hard surfaces. The germicidal activity is reduced by cold temperatures and the soil. Cresol has an offensive odor, is an irritant, and is corrosive, and its color darkens when exposed to light. ### Proper Handling Due to the irritating properties of disinfectants, rubber gloves are recommended when cleaning. When diluting disinfectants with water, follow the directions precisely and do not mix the chemicals stronger than recommended because they may be poisonous to animals. Store disinfectants at room temperature in dark (in nontransparent containers) to maintain germicidal potency. Follow manufacturer disposal instructions. Below are some simple rules for the proper use of disinfectants: - A solution too weak will be ineffective. - A solution too strong is wasteful, may lead to problems of corrosion with equipment and surfaces, and may be harmful to skin and eyes. - No other substance except for water should be added. Combining chemicals can neutralize the effect of the active ingredients, may produce noxious fumes, and cause corrosion. - Be careful when using hot water because spills and splashes may injure operator or patient. - Use recommended contact time. - Using a freshly made solution ensures effectiveness. - Organic material may reduce the effectiveness of the disinfectant and should be removed prior to disinfecting. - Equipment and receptacles used with disinfectants should be thoroughly cleaned and rinsed after use. ### Proper Procedures Since organic matter can inactivate disinfectants, clean surfaces of blood, manure, pus, and soil. Inanimate surfaces with cracks and crevices require attention to ensure proper application. Do not allow animals to have access to the freshly treated surfaces. If liquid disinfectants are used, the surfaces will need to be dry, and if powders are used, the disinfectants need to be degraded, before animals have access. ## Lesson 7: Dietary Management of Small Animals ### Introduction Nutrition and disease interact in two areas. First is the occurrence of undernutrition or overnutrition, such as vitamin deficiencies (e.g., thiamine) or excessive calories (e.g., overfeeding). Using commercially available pet foods that are complete and balanced in nutrition will minimize nutritional deficiencies. Overfeeding and rewarding begging behavior can cause obesity, especially in the inactive pet. Secondly, special diets can aid in the treatment of certain health conditions. Dietary modifications form an important part of nutritional management. Today, there is much interest in this area of veterinary medicine. ### Problems Due to Nutritional Errors - **Obesity** is the accumulation of body fat exceeding the amount needed for optimal body function. This condition can affect the health and well-being of the pet and possibly shorten its life. - Nutritionists suggest that of nutrition related problems occurring among pets, obesity is the most important form of "malnutrition." - Certain dogs and cats seem more prone to obesity. It is unclear whether the primary problem is overfeeding or lack of exercise. Most likely it is a combination of these two factors. Spayed and neutered pets are often less active, which can lead to obesity. - The development of effective weight loss plans for dogs and cats are important aspects of veterinary practice. These weight loss plans should include an exercise program, unless the pet's medical condition limits exercise. Although reduced calorie diets are available, making sure that the pet's owner closely follows the plan is important for its success. If the pet has developed a habit of expecting snacks and treats between feedings, consider this when planning the overall weight loss plan. ### Nutrition and Bone Disease A number of important skeletal diseases result from pet owners feeding their animals improperly. Because minerals form the skeletal structure, diets deficient or improperly balanced in calcium and phosphorus may result in bone problems, especially in young, rapidly growing puppies and kittens. - Vitamins A and D are also important since they aid the absorption of dietary calcium. Remember, supplementation of properly formulated diets for growing animals can also lead to bone problems, especially in large or giant breeds of dogs, like Great Danes. Too much of a nutrient can be just as detrimental as not enough of the same nutrient. ### Nutritional Secondary Hyperparathyroidism Nutritional secondary hyperparathyroidism is a metabolic bone disorder still seen in dogs and cats, despite the fact that prevention results from proper nutrition. The condition displays vague clinical signs, such as weight loss and partial paralysis or pain, and can lead to joint deformity. The most common cause is feeding a calcium-deficient diet to puppies and kittens during growth. - Many pet owners think young animals should be fed only meat because they believe the animal would eat that way in nature. Actually, dogs and cats eat all the parts of the prey they catch, thereby receiving a balanced diet. Their teeth and jaws are particularly suited both to eating and grinding bones, and tearing tough pieces of animal tissues. Their digestive systems are designed to break down these materials. - Feeding animals only meat will cause a calcium deficiency, since calcium content is low in fresh meats. The low calcium diet stimulates the body's production of a hormone called parathyroid hormone. - The parathyroid hormone causes the removal of calcium from bones resulting in weak, brittle bones. These animals may be in pain and can become paralyzed. Prevention of calcium deficiency is preferable to treatment so educating the pet owners about nutrition is a necessity. The use of good quality, completely balanced commercial puppy and kitten food is recommended for this and many other reasons. Pet owners must realize feeding only one type of human food to their pets invites nutritional problems. ### Hypervitaminosis A number of diseases result from the excessive intake of fat soluble vitamins (vitaminsA, D, E, and K). Unlike water soluble vitamins (B and C), which can be excreted in the urine, the body stores fat soluble vitamins, which can build up to toxic levels. - Hypervitaminosis A can cause abnormal bone growth, weight loss, and the animal may display an unhealthy appearance. Caution pet owners to restrict vitamin supplements containing high amounts of vitamin A. Remember, surpluses of required nutrients are not necessarily better. Optimal amounts of each nutrient are most desirable. - Hypervitaminosis A occurs in cats more frequently than in dogs. It can result from excessive vitamin supplements or feeding liver-rich diets. Some cat owners feed only liver to their cats and thereby cause hypervitaminosis A. The owner must realize the importance of feeding complete, balanced diets rather than feeding what they think the pet likes or should have. - Cats given a diet of liver exclusively sometimes resist changing to a proper diet. These cats have learned to like liver and will not readily consume alternative foods. In these instances gradually decrease liver while increasing proper feed. ### Deficiencies of Water Soluble Vitamins Dogs and cats occasionally have nutritional problems related to deficiencies of water soluble vitamins. The symptoms, however, are usually non-specific and difficult to diagnose by physical examination. The animal may be anorectic and lethargic and will have an unhealthy appearance. When the veterinarian suspects vitamin deficiencies, he/she will prescribe a diet adequate in all essential nutrients. Single deficiencies of water soluble vitamins are rare, although problems with thiamine occur. Cats occasionally develop a thiamine deficiency. Thiamine is a water soluble B-complex vitamin. It readily breaks down and loses strength, especially when heated or cooked during the production of most pet foods. Most commercial pet foods add thiamine to compensate for potential losses. Caution pet owners that some fish contain an enzyme that can break down thiamine. - A diet containing raw fish increases the possibility of a thiamine deficiency. Cooking the fish will destroy this problem enzyme and eliminate the potential for thiamine deficiency. Signs of thiamine deficiency usually appear within 1 to 2 weeks after feeding the deficient diet. - Anorexia and weight loss are signs of thiamine deficiency that may progress to include nervous system problems, such as convulsive and ataxia seizures. Injecting thiamine can treat thiamine deficiency unless brain damage has occurred. Feed a balanced diet to prevent this problem. ### Vitamin E Deficiency When diets contain high levels of polyunsaturated fat, remember to include supplemental vitamin E. Some types of fat become oxidized and rancid without vitamin E. - Oxidized fats cause an inflammatory condition of the fatty tissues (adipose tissue) known as pansteatitis. Animals with this condition will be anorectic, lethargic, and feverish (pyrexia). - Cats frequently display vitamin E deficiency after exclusive feeding of slightly spoiled or rancid fish. The recommended dietary therapy is correct feeding of fresh, complete, and properly stored balanced diets. Sometimes, vitamin E injections or capsules may help resolve the immediate clinical disorder. ### Conditions That Respond to Dietary Management - **Chronic Renal Failure** refers to a progressive disorder, which results in destroyed or nonfunctional portions of the kidneys. When this occurs, toxic substances otherwise filtered by the kidneys and excreted in the urine build up in the animal's body. Most of these substances are end products of protein metabolism, but other toxins may accumulate resulting in uremia. - In dogs, dietary management centers on minimizing build-up of protein metabolites, managing phosphorus and related mineral levels, and providing enough dietary calories to prevent excessive weight loss. To accomplish these goals, feed diets low in protein and phosphorus, and higher in fat calories. - In the early stages of disease, it is unclear whether protein restriction will help alleviate the early changes associated with kidney failure. Studies are in progress to help answer this question. When signs of toxin accumulation occur, however, begin dietary phosphorus restriction and switch to mildly restricted protein diets. - In cats, it is more difficult to use protein restricted diets. Cats often refuse to eat protein restricted diets because they do not appeal to their particular tastes. - Commercially prepared feeds for the management of renal failure in cats are available. Veterinarians recommend their use with the caution that some animals will lose interest in these feeds over time. Nonetheless, make every effort to decrease dietary protein and phosphorus to help control this disorder. ### Diabetes Mellitus Diabetes mellitus, a condition that is caused by lack of insulin, can affect both dogs and cats. The major signs include increased appetite, thirst, more frequent urination, and weight loss. The underlying condition is an inability of cells to take up glucose, an important carbohydrate, due to insufficient insulin production. - Elevation of sugar (glucose) levels in the blood and urine rob the body of this important nutrient (glucose) and can damage the kidneys. The goal of dietary management is to provide a consistent calorie intake balanced to the animal's insulin need. Certain diets containing more complex sugars (i.e., starches), including soluble fiber, seem best suited for management of this disorder. - Diets of known, consistent formula and quality in combination with insulin injections help manage this disorder. Timing of feeding is also important to allow food and insulin to work together and supply the necessary nutrients to the pet. ### Feline Lower Urinary Tract Disease Feline lower urinary tract disease, previously termed feline urological syndrome, causes cats to increase the frequency of urination without increasing volume, to strain during urination, to appear listless, and to lick their urogenital area. - Dietary management helps prevent or minimize this problem in cats. The ideal diet helps the animal maintain a low pH and low magnesium content in urine and high urine production. - All responsible pet food manufacturers have generally accounted for these needs in modern pet food formulations. The problem still exists, however, requiring veterinarians to be aware of this often deadly cat disease. ### Congestive Heart Failure Pets with congestive heart failure tend to retain sodium and water in their tissues. Although the reasons are complex, a series of hormonal and metabolic interactions involving the kidneys, heart, and blood vessels is the underlying cause. - The primary goal for dietary intervention is to restrict dietary salt (sodium). The degree of sodium restriction necessary varies for every pet. Drug therapies often increase urination and help remove excess water in tissues. However, this excess urination may cause the loss of water soluble vitamins. Foods manufactured for pets with heart problems contain extra water soluble vitamins to account for these losses. - Pet owners need to modify feeding patterns to provide several small meals during the day. This will help eliminate pressure on the heart and chest cavity due to a full stomach. ### Gastric Dilatation-Volvulus Gastric dilatation-volvulus is usually life-threatening and requires emergency care. This illness is characterized by twisting of the upper bowel, stomach and small intestine causing pain, restlessness, attempts to vomit, fever, and a distended stomach. - Large, deep chested dogs seem to be at risk including: bloodhounds, Borzois, Great Danes, German shepherds, Irish wolfhounds, and Dobermans. - The disorder's true cause is unknown, as is the diet's role in its prevention and management. Abnormal contractions of the gastrointestinal tract may be the cause. Avoid exciting the animal at mealtimes and feed smaller portions more frequently. ### Dietary Allergies The most typical signs of food allergies in dogs and cats are not sneezing and itchy eyes, but changes in the skin, itching (especially over the "rump"), and gastrointestinal problems. Pets with food allergy conditions usually display skin rashes. For correct diagnosis, distinguish between flea and tick related problems, other non-food induced problems, and skin rashes. Vomiting and diarrhea may also be a sign of an allergic reaction. - Diagnosis of food allergies involves eliminating all other possible causes of the skin condition and the use of an “elimination diet.” Formulate elimination diets to contain only a few ingredients. The majority of these ingredients have not previously been fed to the symptomatic animal. If the skin rash clears up, a dietary allergy is proven. - It usually takes 6 to 8 weeks to see improvement. After the pet's condition improves, give the previously fed food or foods to the animal and see if the skin problem returns. Make single ingredient changes to identify specifically the dietary ingredient causing the allergic reaction. Diagnosing a food allergy is quite a detective job. Usually a specific protein is responsible, and identification among the many types of proteins or allergens that exist in feeds is difficult. ### Gastrointestinal Diseases Dietary management is important in control of diarrhea, the major gastrointestinal disease. Diarrhea results from any factor that