Small Animal Nutrition

NUTRIENT TERMS

The terms nutrient, ingredient, formula, and nutrient profile are easily confused and sometimes used interchangeably. Nutrients are fundamental energy and metabolic substrates classified as essential or nonessential. Ingredients are the raw materials used in food compounding. The formula selects and apportions ingredients for a particular diet. The nutrient profile describes the resulting quantitative distribution of the individual nutrients within the finished formula. These definitions are important to understand and distinguish from one another because clients easily confuse them.

Many pet food companies advertise their product as being “unique” or including fine ingredients. In this way, clients are led to believe that the product has a superior nutrient profile when compared with other brands. Although listing ingredients can be useful in evaluating a pet food, the nutritive value cannot be identified solely on an ingredient statement. An analysis of a particular food can give an indication of its nutrient content and the availability of a particular nutrient, but it is the absorptive capability of the nutrient (combined with availability) that lends nutritional value. In other words, digestibility of a food is a measure of the biologic availability. A balanced diet should supply all the key nutrients and energy needed to meet the daily requirements of the animal at its particular life stage.

Feeding a food with higher digestibility may allow animals to consume less of a particular food. Consequently, feeding highly digestible food may be more economical than feeding a less expensive food with lower digestibility. In addition, because more of the food is biologically usable, there is less waste to clean up in the yard. Digestibility of a food is determined by a mathematic equation comparing the amount of a nutrient in the food and the amount of the same nutrient in the feces (Box 12-1). Above-average digestibility can be defined as protein, fat, carbohydrate, and energy digestibility more than or equal to 85%, 90%, 90%, and 85%, respectively. Food higher in fiber will be lower in digestibility

Palatability of a food involves sensory factors, such as taste, smell, color, and even texture of food (Box 12-2). Palatability is an essential component of an animal’s behavior toward a particular food, and first impressions are generally important. Sensory components, such as smell, can entice an anorectic patient to eat, particularly if the food is warm and strong smelling.

Additives are nonenergy, nonnutrient substances purposely added to food to enhance color, flavor, texture, and stability. Preservatives are defined as substances capable of inhibiting food-deteriorating microbes. Protection against microbes can also be achieved by both physical and chemical means, such as in dehydration (dry food), heat (moist and dry food), and chemical treatments (semimoist and some dry food). Many preservatives are organic acids, and their salts are added to retard oxidation, discoloration, or spoilage.

Humectants are preservative additives that bind to water to inhibit mold and fungal growth. Other chemical agents, such as antioxidants, can inhibit oxidation of fatty acids and fat-soluble vitamins, which protects them from becoming rancid and losing potency. Antioxidants, such as vitamins C and E, are natural preservatives.

ENERGY-PRODUCING NUTRIENTS

Carbohydrates can be further broken down into simple sugars, fats into triglycerides, and proteins into amino acids. The digestion, assimilation, and metabolism of each of these nutrients produce chemical energy that is stored in the atomic bonds of “storage molecules,” such as adenosine triphosphate (ATP). Storage molecules are portable and can be moved to any portion of the cell where energy is needed to complete an important job. In the case of ATP, the energy is stored in the bond that holds the last phosphate atom. When the phosphate atom breaks off, energy is released when the bond is broken. The energy can then be used to carry out a cellular process. Much of the energy that is gained from food is used to maintain and repair cell structures, such as the cell wall and the cytoskeleton. Animals that are growing, reproducing, exercising, or healing from an injury or combating a disease process have a higher degree of cellular activity than animals that are not engaged in these activities. These animals have higher energy (nutritional) demands. Oxygen synthesis and transport, heat production, muscle contraction, and the synthesis of new tissue are additional examples of cellular activity that requires energy.

As mentioned, carbohydrates provide the body with energy. The consumption of carbohydrates in excess of the body’s immediate energy needs are stored as glycogen or converted to fat. Carbohydrates include sugars, starches, and fibers.

Sugars are numerous and include monosaccharides (simple sugars) and disaccharides (complicated sugars). Multiple sugars can bond and link to form complex sugar polymers. Polymerized sugars include starch and fiber. Simple sugars and complex sugars are broken down (catabolized) to provide energy, which is stored in the form of ATP. The type of polymer that is formed depends upon the sugar template and the type of polymer bonds in the molecule. Glycogen is an animal-specific starch and can quickly depolymerize into units of glucose. Stores of glycogen, therefore, provide a rapid supply of glucose to tissues when sugar is urgently needed. Most of the glycogen in the body is stored in the liver and in skeletal muscle tissue.

Digestion of carbohydrates and starch is a multifactorial process involving complex microbes and enzymes throughout the digestive tract. Dogs and cats lack certain salivary enzymes; consequently, digestion of starchy substances is not initiated in the mouth. Food is mixed with hydrochloric acids and other proteolytic enzymes in the stomach, where primarily protein is digested. Carbohydrates and starch are primarily digested and absorbed in the small intestine.

Insoluble fibers are referred to as complex carbohydrates, such as cellulose and lignin, and they make up the structural elements of grass, plants, and wood. In the plant kingdom, starches and fibers are numerous and diverse (Box 12-3). Sources of starch include corn, wheat, rice, barley, oats, and potatoes.

Fiber differs from starch in that fiber is indigestible by the monogastric stomach and small intestines, which lack the enzymes needed to decompose them. However, fermentation of fiber does occur in the large intestine of some animals with simple stomachs. The primary function of fiber in companion animals is to increase the bulk and water content of the intestine. This effect finds applications in reducing caloric density for weight-control food while maintaining satiety. Some metabolic and gastrointestinal (GI) tract transit disorders also respond to increased levels of fiber in the food. For example, fiber is an important part of the diet for dogs with diabetes mellitus because it helps to stabilize blood sugar levels by extending the time that nutrients are absorbed.

Fiber is digestible by bacteria and protozoan microbes in the rumen, cecum, and large intestine of grazing animals. Short-chain fatty acids result from fiber digestion, which in turn are transformed into glucose. Thus fiber serves as a major energy source for grazing animals. The role of fiber in the diet generally depends on the physiology of the animal’s digestive tract, but in most species, fiber assists in regulating bowel function. In addition, the products of microbial fermentation (of fiber) play an important role in maintaining normal colonic function by decreasing pathogenic intestinal bacteria and may play a part in preventing intestinal cancer.

NONENERGY-PRODUCING NUTRIENTS

NUTRIENT CONTENT AND FORMS OF PET FOOD

Commercial pet food is prepared with varying amounts of water. Three basic forms are available to the consumer: dry, semimoist, and moist. Dry food typically has 3% to 11% water. Semimoist food has 25% to 35%, and moist food, which is the most palatable to dogs and cats, contains 70% to 83% moisture. Nutrient profiles vary with each type of food so that both high- and low-quality food can be found in every form. Thus the quality of a diet is not related to the percentage of moisture it contains.

Dry food characteristically has lower proteins, fat, and minerals on a dry-matter basis than most moist food. In addition, dry food is produced with higher caloric density and typically costs less than most moist food. Dry food may also provide a dental hygiene benefit, although neither dry food nor hard-baked treats should replace regular dental prophylaxis.

When dry pet food is made, raw ingredients are mixed and moistened into dough. The dough is kneaded, cooked, and processed via extrusion. Extrusion uses high temperatures to fully cook and shape kibbles, which leads to digestibility and palatability. It is the most common method of making dry and semimoist diets, and it is important in killing the microorganisms that may be carried in the raw materials.

Although dry pet food is less palatable than moist forms, they have the advantage of having a lower true cost (Box 12-6). The true cost of feeding is the cost of feeding a pet per day or cost per year. This important concept needs to be explained to the pet owner because there are significant differences between dry and canned food. Evaluating both types of food on a cost-per-pound or a cost-per-calorie basis may result in an economically sound decision. For example, dry food costs approximately one third as much as moist food on a cost-per-calorie basis. In general, dry pet food is the major source of calories in North America. In addition to being cost-effective, dry food is convenient, easy to use, and allows the owner to leave food out for extended periods of time. In this way, pets may eat on an ad-lib basis. Access to unlimited dry food may contribute to obesity; annual health examinations should include body condition scoring and pet food consultation as the animal ages.

Water may be added to create a “gravy” that improves the acceptability of a dry pet food. In addition, palatability may also be improved by mixing dry food with canned food Keep in mind, however, that if dry food is moistened with water and left outside in high temperatures, bacterial proliferation is possible.

Food-borne illnesses can be prevented by ensuring consumption of moist food within a few hours. Certain bacteria (e.g., Bacillus cereus) are found in soil, grains, cereal products, and other food. These bacteria may be found in small numbers in dry pet food and are normally of no health significance. However, they can rapidly increase in number when moisture levels are raised (e.g., adding water or moist food to dry pet food) at room temperature. These bacteria can produce a potent toxin that causes vomiting and diarrhea. Pet owners should be warned not to add water to dry pet food and leave them exposed to high ambient temperatures for prolonged periods. Dry pet food with added water or mixed with moist food are usually safe if consumed within a few hours.

Semimoist and soft-dry food have a moisture content ranging from 25% to 40% and are composed of a meat and cereal mixture extruded into small, attractive shapes. Artificial flavors provide a sweet, savory flavor yielding high palatability. Humectant preservatives and cellophane wrapping provide a reasonable shelf life and convenience to the pet owner. Antimicrobial additives help prevent spoilage or bacterial proliferation. It is important to know that semimoist food has readily available soluble sugars and simple carbohydrate sources that are not recommended in the obese or diabetic animal or any other animal in which blood sugar needs to be regulated. Sodium concentrations may also be elevated in semimoist and soft-dry food and must be used with caution in the pet with cardiovascular disease.

Soft-dry food is the combined result of semimoist and dry products. Such hybrid mixes give the advantages of the dry food enhanced with the palatability found in the semimoist food.

Canned or moist food is typically 70% to 83% water and has three forms: a ration loaf, an all-meat appearance, or processed meats and flours bound into a jellied matrix by gums or alginates. The high palatability of canned food results from a high content of water, protein, fat, and the inherent flavor of animal-source tissue. Moist food requires portion-controlled feeding to prevent overconsumption because most pets prefer canned products to dry food. Most moist food in North America is sold as complete diets, with all nutrients present.

Moist food is preserved with heat sterilization and vacuum techniques to ensure an anaerobic environment. Enamel liners insulate the product and provide excellent nutrient stability. The shelf life ranges from 12 to 18 months, provided care is taken in storing at normal temperatures. Palatability may decrease toward the end of the shelf life.

Moist food has a low caloric density. Moist food is expensive on a per calorie basis because fresh and frozen meat by-product ingredients are more costly than equivalent meals and flours. In addition, higher packaging costs correspond to a higher daily feeding cost to the pet owner.

The use of moist food as a combination mixer with dry food is an acceptable practice to increase palatability and control cost. Note that as the ratio of moist food increases in a mix, the palatability and percentage of fat and protein calories usually

Treats are small food rewards that the pet owner may give as a training aid or to reinforce love or affection. Commercially prepared treats or snacks should not be given in excess because such practice could interfere with normal appetite, dietary balance, and may contribute to obesity (Tables 12-4 and 12-5 ). Chocolate is not recommended because it is toxic in high concentrations. Because treats may be a substantial source of calories and protein for some pets, it is important for the technician to inquire about the use of treats when completing the patient’s history. This is particularly important if the pet suffers from diseases that require dietary restrictions, such as diabetes mellitus, urolithiasis, cardiac and renal insufficiency, and obesity. Commercial treats are not subject to testing as is pet food. Nutritional excesses are common in many commercial pet food treats.

The use of supplements should not be confused with treats. Whereas treats are nutritionally trivial when used in small amounts, the supplement is generally administered to correct a nutritional deficiency. The routine use of supplements is not necessary if the pet is provided with a balanced commercial pet food.

HOME-PREPARED DIETS

Many dog and cat owners prefer to prepare homemade food, despite the fact that most commercial food is easier to use, is less expensive, and provides better nutritional balance. Public interest in homemade diets has increased significantly as a result of the 2007 wheat gluten–related pet food recall. Homemade recipes may not be appropriate for individuals with unique physiologic requirements; consequently, close monitoring of the diet’s efficacy is essential. This may include monitoring weight changes, fecal quality and consistency, food acceptance or refusal, pet activity level, water consumption, complete blood count and serum biochemical changes, and urinalysis changes.

Formulation of a home-prepared diet also requires detailed knowledge of the specific nutrient need, nutritional value of the ingredients, knowledge of any possible dietary interactions, possible deterioration of nutrients during cooking and storage, and consideration of the time and effort required in making such a diet. It is imperative that the owner follow a veterinarian-approved recipe so that a balanced diet is made. There are no human daily supplements that can be added to make a complete and balanced homemade pet diet. If human supplements for vitamins, minerals, and choline are used, splitting the capsules into proper proportions is risky and can easily lead to administration of toxic amounts.

Although it is possible to achieve the same nutrient balance with a homemade food as with a commercially prepared food, it is important for the client to understand that homemade recipes are not tested or evaluated as is commercial pet food. Pet owners interested in feeding a homemade diet should consult with a competent veterinarian or preferably a board certified veterinary nutritionist to obtain a balanced recipe. Veterinarians and technicians together should provide pet owners with recommendations or provide guidelines in assessing homemade food. In addition, the owner’s compliance should be regulated by the veterinary professional and diets kept in conformity with the animal’s needs.

Most homemade recipes have been crudely balanced using the average nutrient content of specific food and computer formulation. Unlike commercial food, few of the numerous published homemade recipes for dogs and cats have been tested to document performance over sustained periods, including tests for palatability, digestibility, and safety. Therefore veterinarians and veterinary technicians should encourage regular dietary histories and patient monitoring for pets fed homemade food. The pet owner must be committed to ensuring consistent, proper homemade food; home-cooked food is more expensive, inconvenient, and requires a major time investment. The purchase of new equipment (kitchen scales that weigh in grams, blender or food processors, etc.) may be required by the pet owner.

The veterinary technician should help evaluate the patient on a homemade diet by noting body weight, body condition score, activity level, and conducting a thorough physical examination. Veterinary technicians should be willing to assess an existing homemade food recipe, offer nutritionally adequate recipes, and make appropriate formula substitutions for clients. Taking the time to counsel clients on the different homemade diets will prevent common problems and increase the client’s compliance.

It should be noted that many homemade diets contain excessive protein and are deficient in calories, calcium, vitamins, and minerals. Most formulations for dogs use staples such as carbohydrates and meat sources containing more phosphorus than calcium, often exceeding the animal’s nutritional requirements. Homemade feline food often is deficient in fat and has low energy density. In addition, no single supplementation can be added to meet the mineral and vitamin requirements found in most commercially prepared food.

PET FOOD LABELS

Pet food regulation varies from country to country; the pet food label represents a contract between the manufacturer and the consumer. The Association of American Feed Control Officials (AAFCO) establishes standards for label information and the description of ingredients on pet food sold in the United States. The AAFCO ensures that adequate information is communicated to the consumer about the food product. The association is made up of representatives from a wide range of professional organizations, including: the American Veterinary Medical Association (AVMA), the American Animal Hospital Association (AAHA), and the Pet Food Institute (PFI). Pet food labels provide useful information that enables both the veterinarian and the pet owner to make decisions about what to feed and how frequently to feed it. It should be noted that in the United States, health claims on pet food labels or in accompanying literature are subject to FDA investigation. Pet food labels are required to state:

Many labels contain more information than what is listed previously. Feeding instructions, caloric content, and a statement that the diet is complete and balanced with respect to a particular life stage are all additional statements commonly found on pet food labels (Figure 12-3). The veterinary professional should counsel clients on how to read a pet food label (e.g., the consumer should consider whether there is a nutritional adequacy statement based on feeding trials and if there is a telephone number on the label for further inquiries).

The nutritional adequacy statements on pet food labels may vary. Nutritional adequacy statements may use terms such as totally nutritious or complete and balanced. By AAFCO regulations, the nutritional adequacy of a food only requires recommended levels of essential nutrients at two different life stages: growth and reproduction. A statement such as “formulated to meet the AAFCO dog food nutrient profile” (or similar wording) only indicates laboratory analysis for a minimal chemical content. Such testing is not an animal feeding performance trial and says nothing about adequacy, bioavailability, or excesses.

The AAFCO establishes minimal standards for testing new pet food products. These protocols are used by pet food manufacturers during feeding trials to substantiate the nutritional adequacy of their product. The AAFCO animal feeding test statement (see Figure 12-3), which is required on pet food labels, lets the consumer know that the product was used in animal feeding tests and that it performed at acceptable levels. Consequently the veterinary technician should recommend feeds to clients that have the “feeding test” information on the label and not the food with the “formulated” statements, if given a choice. It is important to recognize that under current regulations, a pet food company does not have to run feeding trials on each individual product to be able to claim nutritional adequacy.

Nutritional adequacy statements are not needed on treats or snacks intended for intermittent feeding.

There are no government requirements in Canada for the substantiation of nutritional claims on pet food labels. Pet food that meets nutrient standards and passes digestibility feeding trials is given special seals of certification by the Canadian Veterinary Medical Association.

MARKET CATEGORIES

Understanding market objectives for a product may assist with some aspects of assessing a food’s quality. Grocery brands are generally well-recognized pet food sold in grocery stores with large-scale advertisement and distribution. Most grocery brands are all-purpose food, balanced for the growth or lactation life stages (see Pet Food Evaluation). “Premium” grocery bands are specific-purpose food types with a more nutritional focus than traditional grocery brands. Other food types include “gourmet” food to sell the consumer on increased palatability for finicky pets.

Generic (white label) and private label (a grocery chain’s own brand) food is made at contract feed mills using least-cost formulation methods. Private label brands are common in large supermarket settings and pet retail outlets. Markets emphasize low cost and high palatability and generally sell on anthropomorphic appeal. Flavor, shape, color, ingredients, and brand name proliferation characterize these products, allowing them to engage the largest amount of shelf space.

Specialty brand pet food is often sold in veterinary hospitals, pet superstores, and regular stores. Often called “premium” or “super premium” food, they generally stress better-quality ingredients with exceptional nutritional focus. Although differences in nutritional philosophy may be noted among different manufacturers, these brands are consistent in the overall objective of emphasizing a philosophy of optimal nutrition. This specialty brand food typically uses the life-stage and special-needs approach, with a general aim at disease prevention.

ENERGY REQUIREMENTS

An estimate of the energy requirement of an animal is needed to determine how much food to feed. If you recall from the Energy Producing Nutrients section of this chapter, the nutrients that provide energy include proteins, carbohydrates, and fats. When these nutrients are burned, they release energy in the form of heat. Each nutrient releases a different amount of heat, which is measured in kilocalories, or Calories (note the upper case “C”). A kilocalorie is the amount of heat (energy) needed to raise the temperature of 1 kg of water 1° C. With this in mind, the energy requirements (food) of an animal would be calculated and expressed in kilocalories.

Daily energy requirements are the number of calories needed to maintain an animal’s weight. Obviously an increase in the animal’s exercise, lactation, and growth would increase energy requirements, whereas a decrease in these activities would lower energy requirements. Increased energy demands over and above the needs for maintenance are called production energy requirements.

Predictive equations are useful in calculating nutrient requirements, but judging the body composition and condition of the animal is also important in determining the caloric needs of the animal. Body condition can be assessed by feeling the ribs with flat palms. Ideally the ribs should be felt, but not seen (Figure 12-4).

Body condition scoring gives the veterinary professional an estimate of an animal’s body composition. The body condition score can subjectively assess a pet’s fat stores and muscle mass. Note that the body condition scoring system was developed with regard to both age and species.

NUTRITIONAL ASSESSMENT

A thorough nutritional assessment consists of a patient’s history and a physical examination including body weight, body condition scoring, and hydration status. The primary goal of nutritional assessment is to identify the dietary needs of the patient. In the course of a disease or treatment process, a patient’s nutritional needs can change, and these changes need to be monitored regularly and discussed with the pet owner.

A baseline nutritional assessment should be made upon admission to the hospital and followed by serial assessments throughout the course of the hospitalization (see Clinical Nutrition). The veterinary technician is particularly well positioned to identify baseline data and ongoing changes in nutritional status because the technician typically spends the greatest amount of time with hospitalized patients. Nutritional intervention is crucial to recovery and survival, particularly with the critical patient, and appropriate consideration as to the type and route of nutrition should be given based on the underlying disease process or diagnosis (see Routes of Feeding and Tube Selection).

FEEDING DOGS

Dogs are typically omnivores and exhibit eating behaviors similar to their relatives the wolf (Canis lupus) and the coyote (Canis latrans). Dogs are opportunistic eaters, predators, and scavengers and have developed anatomic and physiologic traits that allow for the digestion of a variety of food. Although dogs are omnivorous, pet food advertising emphasizes the carnivorous aspects of the canine diet (“meatier is better”). Many domesticated dogs eat vegetables, grains and pastas, meat, processed food, various dairy products, and fruit. Some pet owners complain that their dog eats grass and feces, though such behavior is natural. Cayenne pepper sauce on feces has been helpful in reducing their dog’s objectionable behavior.

Because dogs range in size, age, and activity level, nutritional energy requirements are calculated based on the animal’s metabolic body weight, or the weight of actively metabolizing tissue. Variations in body composition and breed are also considered. In addition, nutritional requirements should be based on the particular life stage to achieve biologic performance and overall good health (Table 12-6).

^∗Nutrients are expressed as % dry matter. Energy is expressed as kcal metabolizable energy (ME) per gram dry matter.

^†Older animals require frequent body condition scoring. Feed intake adjustment may be required to maintain an ideal body condition because some older individuals tend to be heavy and others tend to lose weigh.

Canine Pediatric Nutrition

Milk provides a complete food source for neonates, containing water, protein, fat, vitamins, and minerals. Colostrum is the key nutritional factor immediately after birth. Owners should ensure that the dam is producing colostrum and that the puppies are consuming it. This is particularly pertinent if the bitch delivered the puppies via cesarean section. Colostrum provides fluid for vital postpartum circulatory expansion and carries protective maternal antibodies that are absorbed through the intestine of the puppies. Colostrum is somewhat sticky and viscous, which can make nursing more difficult in the weaker puppy.

Most puppies are healthy and are capable of active nursing. Ensure that the mothers are lactating well and are attentive to the litter. In general, no assistance is needed from the technician or owner. Exceptions may include extremely small, toy-breed puppies for which frequent, assisted hand feedings may be needed to prevent hypothermia and hypoglycemia.

Technicians should advise clients to weigh their puppies if there is concern about poor milk production by the dam or an inadequate consumption of milk by the pups. The examination and expression of the mammary glands is also helpful when assessing milk production. Regular checks are important to ensure good milk flow and to make an early detection of mastitis or other mammary gland complications.

The normal growth rate for puppies is 2 to 4 g/day/kg of anticipated adult weight. Weight gain below this rate and accompanied by restless, hungry-seeming puppies is generally a sign that the puppies are not receiving adequate amounts of milk.

Feeding Orphan Puppies

Neonatal puppies that are unable to nurse should be fed a canine milk replacement formula. Canine milk is higher in protein and lower in lactose than bovine milk; consequently, water should be used to mix the replacement formula and not cow’s milk.

The orphan formula dose is initially 15% of the puppy’s weight per day divided into several doses. The process of feeding puppies can be facilitated by using a syringe and a flexible, rubber feeding tube (Figure 12-5). If the animal has a strong suckling reflex, a small animal nursing bottle or doll’s baby bottle may be used. The nipple may be pierced with a hot needle so that a drop forms over 1 to 2 seconds when the full bottle is tipped upside down. A syringe or eyedropper is not recommended, but can be used in an urgent situation where a bottle is not available. It is essential to deliver the liquid into the mouth slowly to prevent aspiration.

If a feeding tube is used, care must be taken not to place it in the trachea. The stomach capacity of the neonate is approximately 50 ml/kg. Initially, puppies are fed 10 ml q 4 to 6 hours, and kittens are fed 5 ml q 4 to 6 hours. The amount is gradually increased by 1 ml/feeding (dog) or 1 ml/day (cat) until the recommended guidelines are reached. Although feeding frequencies vary, generally the first 3 days of life are the most critical.

Typically the stomach is full from feeding when the belly is distended or the animal turns its head away from the nursing bottle and squirms. New formula should be made at each feeding and not stored reconstituted to prevent bacterial contamination. Food substances should be room temperature before administration. All equipment should be meticulously clean or sterile. Before the litter of puppies is discharged, the veterinary technician should pretest the flow rate from each of the nipples and give explicit instructions for keeping the system clean. When the puppy reaches 2 to 3 weeks of age, the food dose should approximate 25% of the body weight divided into four to six daily feedings. Monitoring weight gain by the use of a gram scale is a good way to evaluate food intake.

If the puppies are unable to consume formula or dam’s milk on their own, a 5F or 8F infant feeding tube is typically used for gavage. Placement techniques include measuring from the tip of the nose to the last rib, marking the tube, and passing it down the left side of the mouth. A gag reflex is not present until 10 days, but easy passage to the premeasured distance usually indicates correct placement. After delivery of the fluid, kink the tube before withdrawal and withdraw it quickly to prevent aspiration. The animal should be burped after feeding by holding it at a 45-degree angle, massaging the stomach, and patting it gently on the back with fingertips only. The residual stomach volume should be measured by the gentle aspiration of stomach contents (which are then returned to the stomach) before each treatment or feeding to document that fluids are being absorbed and gastric motility is adequate.

When the puppies are able to eat solid food on their own, small amounts of food should be given incrementally until the puppies become content. Satiation is often indicated when the puppies become quiet and fall asleep.

Low birth weight is correlated with an increase in mortality. Puppies with low body weights are more prone to hypoglycemia, hypothermia, and sepsis. The bitch should also be monitored for behavior changes toward any particular pup because the bitch may shun hypothermic and ill puppies. Because body fat is generally low in puppies, the environment should be kept between 84° F and 90° F.

Eternal warming should always be provided if the neonate is separated from its mother. Warming protocols should include the use of circulating hot water blankets only; electric heating pads are not recommended. Other alternatives include warmed rice bags, hot water bottles, heat lamps, or Bair Hugger units, if hospitalized. A pan of water can increase the humidity in the environment. Neonatal incubators can be used to provide a temperature of 85° F to 90° F and a humidity of 55% to 65%.

Whichever heat source is used, the neonate should be able to crawl away from the heat source and the temperature monitored at least every 20 to 30 minutes on the recumbent patient. A thermometer should be placed near the neonate to check the ambient temperature. Hypothermia is common in neonates and is associated with shallow respirations, bradycardia, GI paralysis, and coma. Feeding is contraindicated if the animal is hypothermic (<94° F) because GI motility and digestive function can be impaired.

The neonatal body temperature should be increased slowly. The most effective method is the use of warm inspired air because it warms the core and the external shell (such as provided by the Bair Hugger units, if hospitalized) or an incubator or heated oxygen cage.

Constipation or diarrhea may occur with formula feeding. If diarrhea occurs, the formula should be diluted 1:2 with a balanced electrolyte solution until diarrhea resolves. During the administration of food substrates, the patient’s response may not be typical because the gag reflex does not develop until 10 days of age. Consequently, care should be given for the proper placement of a feeding tube. A baseline birth weight should be recorded; healthy puppies are expected to gain 1 to 1.5 g daily for each pound of anticipated adult weight. Assist elimination every 2 to 4 hours (or after each feeding) for up to 4 weeks using cotton balls soaked in warm water to wipe the caudal abdomen and anogenital region. Wipe down the entire animal with a slightly damp, warm face cloth or soft nailbrush one to two times per day.

Weaning Puppies

Peak lactation occurs at 4 weeks, and weaning concludes at 6 to 8 weeks. Begin introducing puppies to semisolid gruel made from two parts of water to 1 part high-quality, dry, canine growth-lactation pet food. Three weeks of age is a suitable time to introduce a semisolid gruel, except for toy breeds and weak animals, which need more time before they are offered solid food. Gruel can be finely chopped or mashed and placed in a shallow bowl for easy consumption. This serves as an important transition food and acclimates puppies to eating solid food. At 5 weeks of age, puppies are reducing their intake of mother’s milk and are consuming larger amounts of gruel. The ratio of water can be reduced as the puppies are slowly moved from semisolid to solid food. After weaning, the ability for the pup to digest lactose becomes less efficient. Consequently, it is important to avoid feeding weaned dogs large quantities of milk, which might cause diarrhea. In addition, puppies can exhibit competitive eating as early as 5 weeks of age; puppies should be supervised during feeding to ensure adequate and equal consumption.

Feeding Growing Dogs

Proper nutrition for growing dogs is essential for normal growth and development. An excessive intake, however, can lead to medical complications. Overfeeding, for example, can result in obesity in small breeds and rapid growth rates in large-breed dogs. Inciting stress on the juvenile skeleton by overfeeding in the large breeds can cause abnormalities, such as osteochondritis, hip dysplasia, panosteitis, and wobbler’s syndrome. Nutritional requirements change rapidly during a puppy’s growth, with growth rates varying between dog breeds. Nutrient guidelines for small- and medium-breed versus large- and giant-breed dogs are listed in Table 12-6. Supplements are generally not needed if the puppies are fed name-brand commercial diets.

Most growing puppies eat four or five times daily during the postweaning period, or until about 10 weeks of age. Meal frequency should be cut to three meals a day until they have reached approximately 50% of their adult body weight, or approximately 4 months of age. Technicians should advise pet owners to feed small meals several times a day and not allow the puppies continuous access to food because many puppies will overeat when fed ad lib.

Growing Concerns For Large-Breed Dogs

Research studies have documented that improper feeding during growth is associated with several skeletal disorders in large-breed dogs. About 22% of dogs less than 1 year of age are affected by developmental skeletal disorders, and more than 90% of these cases are influenced by nutritional factors. Such nutritional factors include free-choice feeding of a diet with excess calories and supplementing calcium during the growth phase. The onset of bone developmental disorders is usually associated with rapid growth of the long bones. As previously mentioned, the most common of these disorders are canine hip dysplasia, osteochondrosis, and hypertrophic osteodystrophy.

Calcium and dietary fat are, however, key nutrients for growing puppies. Unfortunately, some growth types of pet food contains excessive amounts of calcium, even at appropriate levels of dry-matter intake. A study of two populations of Labrador retriever puppies examined the effects of nutritional excess. One group ate ad lib, and the second group was limited to 75% of the ad-lib quantity. Serial pelvic radiography for 2 years showed significant reductions in hip laxity in the meal-limited group.

To help control the risk of abnormal orthopedic development in large- and giant-breed puppies, experts recommend that the caloric content for large-breed dogs should be less than that for smaller breeds and should contain no more than 12% fat on a dry-matter basis.

Feeding Adult Dogs

The primary objective in feeding the adult dog is to find the maintenance energy requirement and proper food dose to maintain the ideal body composition. Recommended nutrient guidelines for adult dogs are found in Table 12-6. Note that in the adult dog, ad-lib feeding is commonly associated with over consumption and obesity.

The amount of feed needed to meet energy requirements is based upon the energy value of the food. Activity levels also vary between dogs and should be taken into consideration when compiling a feeding protocol. Diverse canine breeds, specifically the variation in breed size, may reflect different metabolic rates and different growth rates. For example, small and toy breeds have a higher energy requirement per unit of body weight than the large and giant breeds because basal metabolic rate is related to total body surface area. Since the smaller breeds have a higher ratio of surface area to body weight than large breeds, they require more energy per unit of weight (lb or kg). In addition, the small breeds have relatively small stomachs, so their ability to consume food is somewhat limited. Consequently, small-breed diets should have a higher energy content and a more nutrient-dense matrix than diets designed for larger breeds. High digestibility is also an important consideration so that optimal nutrition can be provided in small meals. Small, kibble-size dry food should also be considered to aid in chewing and consumption.

Regular weighing and body condition scoring will allow both technician and owner to assess the adequacy of feeding. In addition, environment plays a key factor in energy expenditure. Note that by spaying an animal, energy requirements may decrease 10%; consequently, adjustments in diet may be necessary to prevent weight gain.

Feeding each pet separately is best, whenever possible. In the time-restricted method, feed each dog from one to three times daily with ad-lib consumption for 5 to 15 minutes. If the dog consistently leaves a little food in its dish and also maintains an ideal body condition, the conclusion must be that the animal is self-regulating its food intake at its energy requirement.

Time-restricted feeding works well for many dogs and their owners; however, some dogs ravenously overeat during the allotted time. In dogs that overeat, try volume-restricted meal feeding by serving a calculated food dose. To determine the daily volume, divide the energy requirement by the food’s caloric density. Then feed one half to one third of the daily volume two or three times per day. An average caloric density guideline for pet food is listed in Table 12-6. Other aids for calculating how much food to feed are: the feeding instructions found on the pet food label, food dose calculators, and technical information from manufacturers. Maintenance pet food is recommended for the average house pet who is 1 to 7 years of age.

It is recommended that table food be eliminated or used in moderation (10% or less). Fat trimmings quickly unbalance a base diet and lead to finicky behavior and a predisposition to obesity. Avoid feeding animal bones because sharp fragments may wedge between teeth, lacerate the esophagus, or cause GI obstruction or constipation. Nylon bones and chew toys are safer substitutes for natural bones, but still cause problems in some individuals. Table 12-6 lists guidelines for assessing pet food used in life-stage feeding.

It is best for each dog to be fed individually; however, as a result of time and labor costs, this may be impractical in animal colonies and kennels. Problems associated with group feeding include anorexia in the timid animal and overconsumption in the aggressive or dominant dog. Group feeding may also result in competitive eating. Competitive eating can trigger quick consumption of food, initiating gastric distention from swallowing or quickly gulping air (aerophagia). In larger breeds, aerophagia may predispose the animal to gastric dilation and torsion. Box 12-7 lists general feeding guidelines.

It is common for the boarded animal to be stressed or compromised and as a result stop eating. The late detection of anorexia may lead to significant medical consequences for the animals not having an adequate intake. Technicians should frequently assess the appetite of boarding animals and feed on an individual basis.

Feeding Adult Dogs With Increased Energy Needs

Increases in physical activity require extra energy to support increased muscular action. Diet and feeding protocols vary according to training schedules and the amount of work performed. Supplying extra energy to working dogs by using pet food with increased fat, caloric density, and digestibility will allow optimal performance. In addition, feeding diets with extra energy content allows dry-matter intake and gastric fill to remain at familiar, nonexcessive levels. Increasing the quantity or frequency of a regular food is a secondary option to increase performance.

The specific nutrient composition of diets for working dogs varies and depends upon the type of activity performed. In general, staples include fats and carbohydrates for intense muscular exercise. Note that in the sprinting or racing dog, short and intense bursts of energy are required, typically obtained by readily available muscle glycogen stores. Large quantities of carbohydrates may be useful because this may help maximize muscle glycogen reserves.

On the other hand, diets high in carbohydrates may be counterproductive in other working dogs and may even reduce athletic performance. High-carbohydrate diets may lead to lactic acid accumulation during prolonged exercise, resulting in muscle fatigue and/or damage. Endurance dogs therefore may benefit from higher fat diets because their muscle activity is powered primarily by aerobic fatty acid oxidation (approximately 70% to 90%).

Animals can be aerobically conditioned before extensive fieldwork. Aerobic training increases the efficiency of fatty acid metabolism in the muscles and the cardiovascular system. Such aerobic conditioning spares the rate of glycogen consumption in muscles and increases the capacity for work. At the start of aerobic conditioning, technicians can advise clients to slowly convert the dog to a more calorie-dense food and suggest feeding the majority of daily calories after the completion of training to help prevent hypoglycemia. This is particularly pertinent in hunting dogs.

Unfortunately, most clients feed the caloric-dense food before work or training. Subsequently, after the meals’ digestion, insulin is released as a result of glucose absorption, allowing for a high rate of glucose transfer into the cells. If the animal simultaneously begins hard work, the combination of the two glucose-consuming activities may precipitate hypoglycemia. If working dogs show consistent signs of hypoglycemia, even after conditioning, they may be fed 10% to 15% of the daily calorie dose as a light feeding at 2-hour intervals during work. Clients should also be reminded of the importance of an adequate water intake throughout the work period.

Feeding During Pregnancy and Lactation

During lactation, a proper nutrient intake is directly linked to successful milk production. Technicians should recommend a growth-lactation formula to meet the increased requirements. Lactation markedly increases energy, protein, and mineral requirements; nutrient requirements during lactation are greater than at any other adult life stage. After whelping, the bitch returns to her regular body weight (Figure 12-6). Expect the food intake to rise rapidly by 50% the first week and by 200% to 400% by the fourth week of lactation. Free-choice food should be available to the bitch. The water intake should also be monitored because water is the most important nutrient during lactation. After whelping, energy requirements return to maintenance levels in approximately 8 weeks. Frequent physical examinations should be performed to maintain normal health and to assess the adequacy of the diet.

Key nutritional factors in the lactating bitch include highly digestible protein, increased concentrations of fat (in proportion with other nutrients), 10% to 20% soluble carbohydrates, and approximately two to five times more calcium than during the maintenance life stage (Table 12-7). Supplements are generally not needed for normal animals when high-quality pet food is used.

Feeding Methods During Weaning

The food intake should be terminated for 24 hours to help the bitch slow and stop her milk production. Restricting food will reduce nutrients needed for milk production, resulting in mammary gland reduction. Technicians should advise clients not to allow any puppies to nurse because such practices do not alleviate mammary gland engorgement and may stimulate milk production.

The food intake for the bitch can be resumed using maintenance food at one third of the customary maintenance level. On the second day, two thirds of the normal feeding dose is recommended, with a full intake on day three. As lactation quickly dries from acute calorie deprivation, the bitch will more readily reject the puppies’ attempts to continue to nurse.

Obesity-Prone Animals

Feeding Geriatric Dogs

The definition of geriatric as it pertains to the dog is not precise because of breed variability. In general, toy and small-sized breeds are geriatric at 7 years, medium-sized dogs at 6 years, and large and giant breeds as early as 5 years of age.

Geriatric pets undergo physiologic changes similar to elderly humans. Older animals, for example, have a higher incidence of multiple organ failure, benign and malignant tumor formation, osteoarthritis, dental disease, and loss of hearing and vision. Age-associated changes in physiologic function include reduced immune response, reduced digestive and renal function, reduced glucose tolerance, and smell and/or taste perception changes. Unfortunately, no specific diet or nutrient formula can delay the onset of disease or slow down the aging process. However, the dietary practices in the first three fourths of an animal’s life can impact the nutritional consequences manifested in the last part of its life (Burkholder, 1999). Older pets become less active and have reduced lean body mass and have a reduced basal metabolic rate.

Nutritional recommendations for the geriatric pet should be influenced by the individual body condition and health history. The ideal goal in geriatric animals is the maintenance of optimum weight. Commercially available senior diets should be evaluated and only recommended based on the status of the animal. Dietary modifications should be considered if a particular disease state could be ameliorated by the absence or presence of a particular nutrient. Pet food specifically intended for seniors emphasizes moderate energy density with good palatability and reductions of some excess nutrients, as found in all-purpose pet food.

Senior food varies depending upon the manufacturer. Common nutritional factors to take into consideration when recommending a balanced senior diet in the healthy pet include reduced protein, reduced phosphorus and sodium, and increased fiber concentrations. Keep in mind that healthy older cats should not be fed a low-protein diet just because they are old; limiting protein in cats with normal renal and hepatic function can contribute to muscle loss.

Age-related behavioral changes, such as disorientation, owner interaction changes, disturbances in sleep, and loss of bladder or bowel control, may be ameliorated by diets enhanced with antioxidant formulations (Head, Zicker, 2001). Specific therapeutic diets are now available that may help combat the signs of brain aging and improve the learning ability of senior dogs. Exclusive blends of antioxidants and other nutrient formulations help protect against free radical damage, improve cell membrane health, and optimize senior health.

Calorie control may begin or be continued in some older animals. However, blanket feeding recommendations based solely on age are unwise without consideration of the individual. For example, though many geriatric animals have a propensity to put on weight, there are many that lose weight. Weight loss may be a symptom of systemic illness, dental or oral pain, a failing sense of smell, or heightened finicky tastes or fixed food addictions.

Feline Pediatric Nutrition

An adequate colostrum intake for all kittens is critical and should be monitored immediately after birth. Like puppies, the orphaned kitten can be raised by tube lavage or pet nurser systems to administer milk replacement (Figure 12-8). It is important to ensure the correct placement of a gastric tube to prevent pulmonary aspiration. Stable environmental factors for pediatric felines are similar to pediatric canines; warm, dry bedding is paramount. Heating pads should cover only half the box for kittens and mother to crawl away from the heat source if it is too hot (see Feeding Orphaned Puppies). In addition, orphaned kittens may need assistance in urination and defecation, similar to orphaned puppies.

Kittens weigh between 85 and 120 g at birth and gain an average of approximately 100 g/week (McCune, 2003). Similar to canine pediatric care, the use of gram scales to monitor weight as an indicator for a proper nutrient intake is recommended. Caloric needs for most puppies and kittens are 22 to 26 kcal/100 g of body weight for the first 3 months of life. Feedings should be scheduled at least four times a day. In general, male kittens grow faster than females.

The formula should be warmed to about 100° F (37.8° C) before feeding. The initial feedings should have less volume (but not frequency) than those directed by the manufacturer. Over the next several days, gradually increase the volume of formula to the amount recommended by the manufacturer. Subsequent increases will be needed based on weight gain and satiation. The formula preparation should follow label instructions, and all feeding equipment must be cleaned immediately after use. The stomach capacity of the neonate is approximately 50 ml/kg. Initially, kittens are fed 5 ml every 4 to 6 hours. The amount is gradually increased by 1 ml/day until the recommended guidelines are reached. Although feeding frequencies vary, generally the first 3 days of life are the most critical.

Kittens are weaned later than puppies—generally at 7 to 9 weeks. Growth-sustaining kitten food are fed two or three times daily until the kitten is 10 months of age.

Feeding Adult Cats

During the adult maintenance life stage, it is recommended to feed a consistent diet and employ a feeding schedule to eliminate finicky behavior and food aversion.

The technician may encounter owners that vary food types as a response to the large number of cat food flavors on supermarket shelves. Providing a variety of flavors is unnecessary, and a transient “newness” factor can temporarily increase food intake and can lead to weight fluctuations.

Most cat owners tend to feed ad lib. When allowed continuous access to food, cats usually eat small, frequent meals throughout the day. A common belief is that cats are better than dogs at maintaining their body condition. However, the latest epidemiologic studies no longer support this idea. When offered a highly palatable, high-fat diet, cats fed ad lib tend to overeat, especially if they are neutered or lead a sedentary lifestyle. A survey of 500 practitioners showed that although most clients were aware of the potential for weight gain in their sterilized cats, only 10% of the veterinarians recommended that the cats be switched to a low-fat diet (Biourge, 2001).

Commercial feline treats are usually nutritionally synonymous with dry cat food (see Table 12-5). As such, they are appropriate to be used as treats, but only if given in moderation. Some cat owners prefer “natural” treats, such as raw or cooked poultry necks, oxtails, or liver. Although little harm results from the use of these treats in moderation, finicky behavior and subsequent nutritional imbalance are potential hazards. Specifically, liver contains an inverted Ca/P ratio (1:17), and potentially toxic levels of vitamin A (hypervitaminosis A) can occur with long-term consumption.

Hairballs occur commonly in cats because of their meticulous grooming habits and the sharp barbs on their tongues, which increase the apprehension and consumption of hair. Hairballs are periodically regurgitated from the oropharynx or esophagus or vomited from the stomach. Occasionally, hairballs pass into the intestinal tract where they are voided in the feces. Owners may observe periodic gagging, retching, and regurgitation or vomiting of hair and mucus. Hairballs are often tubular and usually do not contain food or bile. Although hairballs do not usually cause significant clinical disease, they can be of concern to the owner. Many laxatives, lubricants, treats, and food are available for routine management of these problems. Laxatives and lubricants should be used intermittently because large daily doses may interfere with normal digestion and nutrient absorption. Several complete and balanced moderate-fiber food is now available for control of hairball problems in cats.

Feeding Cats During Pregnancy and Lactation

During the reproductive life stage, energy and nutrient requirements must support both queen and offspring during pregnancy, lactation, and milk production. At peak lactation, energy and nutrient requirements can be three to four times normal maintenance. Because ingesting larger amounts of food may not be feasible, owners can feed a diet that is more energy and nutrient dense, with increased digestibility to reduce bulk. It is important to advise clients that supplementation, with vitamins and minerals, is not necessary as long as the queen is fed a balanced diet.

There are significant differences in the food intake between the bitch and the queen during the initial stages of lactation (see Figure 12-6). As a solitary hunter, the queen hunts less during the early part of lactation and uses the body fat stored during gestation to support her milk production. The practical significance here is that clients may question a low food consumption in their new mother cat. Such clients can be advised that the queen will eat heavily, as expected, by the third week of lactation.

Feeding Geriatric Cats

An evaluation of the geriatric individual is crucial in determining an appropriate food that will maintain a proper body weight and still provide adequate nutrient levels. In selecting the optimal diet for an older cat, overall health must be considered. The food intake should be monitored in association with changes in weight. Hyperthyroidism, for example, is characterized by chronic weight loss despite a ravenous appetite. The water intake should be noted since an increased frequency of drinking and urination may also be symptomatic of disease.

No single food can meet the needs of every geriatric cat. Dietary modification can help to optimize health in the healthy cat and to modulate disease in cats as they age. Significant protein restriction is not recommended in the healthy geriatric cat because of the high protein requirements in felines (see Amino Acids and Proteins). A moderate restriction of protein is recommended for the cat with evidence of chronic renal failure (see Clinical Nutrition). Commercial diets are available with balanced nutrient contents for optimizing the health of the elderly cat. Oral hygiene is an important factor in feline geriatrics; routine dental examinations should be performed to ensure that there is no tooth pain and that food can be apprehended and chewed.

Similar to geriatric canine nutrition, certain dietary adjustments can help improve clinical signs or even slow progression of disease (see Feeding the Geriatric Animal). The best diet, however, should be based on the individual cat’s clinical signs, body condition score, laboratory results, and stage of disease.

Feline Obesity

Feline obesity, like canine obesity, is a common nutritional problem. One important role of the technician is to educate the client and to encourage participation in weight-reduction programs. A detailed dietary history is helpful when calculating the amount of food that will be offered during a caloric-restricted diet. Fasting in obese cats is not recommended because fasting has been associated with the accumulation of lipid in the liver. This can become pathologic over a 5- to 6-week period, and it mimics idiopathic feline hepatic lipidosis (Figure 12-9).

Obesity can be prevented if the veterinarian and the technician provide nutritional counseling during routine yearly examinations. In addition, the owners of felines that have a gonadectomy should also be counseled as to the amount of food given after surgery to prevent excessive weight gain. Dietary therapy should only be instituted after a complete physical examination, biochemical profiling, and compilation of medical history. It is important to instruct the client to gradually introduce a new food over a period of 7 days. Obese cats that are given a new diet all at once may become anorexic.

Statistics show that cats being fed high-fat (±20%) premium and superpremium diets are two to three times more likely to become overweight. Conversely, cats fed a diet containing around 10% fat are 50% less likely to be overweight. Dietary recommendations for feline obesity include feeding multiple small meals throughout the day to optimize digestive and absorptive energy expenditures. Traditionally, diets are composed of low-calorie, high-fiber substances. Recommendations for caloric restriction range from 50% to 80% of maintenance calories to achieve optimum weight (Burkholder, 2000). Commercial and prescription canned diets are now available that are tailored for the obese cat. Such canned food includes a low-carbohydrate, high-protein matrix. Cats fed some (50% is a good starting point) tailored canned food as part of their diet will reduce the carbohydrates and better control calories (dry food is very calorie dense) and will help increase the amount of water consumed daily. In addition, low-carbohydrate, high-protein formula have been clinically proven to alter a cat’s metabolism for effective weight loss and may help prevent diabetes mellitus in the aging feline. The addition of L-carnitine also helps the feline patient lose weight while maintaining lean muscle mass and decreasing the accumulation of fat in liver cells.

Feline Urolithiasis and Lower Urinary Tract Diseases

The two most common calculi that occur in cats are struvite and calcium oxalate calculi, both of which can lead to lower urinary tract diseases. The amount and balance of mineral elements in the diet of a cat can have significant effects on the formation of urinary calculi. Other important factors in calculi formation include urinary pH, urine concentration, and high dietary magnesium. Although there are many factors that can contribute to the formation of uroliths that are related to diet, uroliths are rarely, if ever, the direct result of diet. The diet can, however, have an impact on the urinary concentration of calculogenic substances.

The water intake is a major factor in determining urine concentration and to some extent frequency of urination. Other factors that can affect urine concentration include the sodium, fat, and carbohydrate content because energy metabolism results in the production of metabolic water. The digestibility of the diet will also determine the amount of water lost in the stool and the quantity of minerals that are absorbed and ultimately excreted. Other aspects of diet that can influence the development of uroliths include the dietary content of minerals, quantity of diet consumed, and the influence of diet and eating frequency on urine pH because some uroliths are more or less soluble in certain pH ranges.

Certain feline diets are formulated to induce acidic urine because of the addition of acidifiers, such as methionine, ammonium chloride, and phosphoric acid. Struvite crystal formation is not possible at a urine pH below 6.5. Particular animal proteins and corn glutens found in feline diets can also promote acidic urine, as opposed to diets composed of vegetable proteins and mineral salts, such as calcium carbonate, which promote alkaline urine.

Urine acidification is not without potential toxicity. Excessive acidity can overpower the ability of the kidneys to excrete protons and induce uncompensated metabolic acidosis. Consequently, chronic acidosis in cats can increase urinary potassium losses and could potentially slow growth, increase urine calcium excretion, and promote bone demineralization.

Acidifiers also can be toxic. Acidifying diets are recommended to safely prevent and manage struvite-related lower urinary tract disease (LUTD). Technicians should refer to the veterinarian before recommending any acidifying diets. These diets are not recommended for kittens because they are not formulated for growth and may interfere with bone formation.

Acidifying diets may also be contraindicated in the older cat; older felines are at a higher risk for calcium oxalate urolith formation and renal insufficiency. No diet will promote the dissolution of calcium oxalate uroliths, but minimize the risk of crystal formation, diets for mature and older cats should be formulated to induce a higher urinary pH. Maintaining urine acidity (pH 6.2 to 6.4) and keeping the magnesium intake at nonexcessive levels are prudent risk-control measures for struvite crystalluria. Maintaining a more alkaline urine pH (6.4 to 6.8) while avoiding excess calcium, sodium, and magnesium are prudent risk-control measures for calcium oxalate crystalluria. It is also beneficial to increase the cat’s water consumption. Feeding a canned food will decrease the cat’s urine specific gravity and increase the overall volume of urine, thus decreasing the possibility of crystal formation.

Note that the main difference between canine and feline urolithiasis is that struvite uroliths are usually associated with urinary tract infections in the dog. Feline struvite uroliths are generally sterile. Bacteria, such as staphylococci and other urease-producing organisms, generally create an alkaline environment, which enhances the formation of struvite and other uroliths. Antibiotic therapy is therefore only recommended in patients with a positive urine culture.

It is an oversimplification to state that controlling urine mineral concentrations or pH always controls feline lower urinary tract disease (FLUTD). FLUTD syndrome is multifactorial; not all causative agents or combinations of contributory factors are presently known. The term idiopathic FLUTD is used in cats where there is no known cause. Potential causes of idiopathic FLUTD include a viral infection, stress, and neurogenic inflammation. Idiopathic FLUTD is not well understood; however, water seems to be a key factor in controlling the recurrence of the disease. Canned and other high-moisture food increases total urine volume and are the preferred products for cats with idiopathic FLUTD.

FLUTD is typically caused by struvite uroliths or urethral plugs, calcium oxalate uroliths, or by a syndrome known as feline idiopathic cystitis (FIC). Clinical signs of FLUTD include urinating outside the litter box, frequency of urination, and/or straining to urinate. Prescription diets are now available that are formulated to provide nutritional management in feline patients with either struvite or calcium oxalate uroliths or FIC. Such diets contain controlled levels of magnesium, calcium, phosphorus, and oxalate to reduce building materials needed to construct potentially harmful crystals and uroliths. In addition, certain specialized prescription feline urinary diets contain limited sodium and high levels of omega-3 fatty acids that may inhibit the inflammatory cascade associated with FLUTD.

Routes of Feeding

Chelonians

Land tortoises are primarily herbivores, but will occasionally eat insects and small rodents. In captivity, diets should primarily be composed of vegetables (mainly dark leafy greens, grasses, and weeds), some fruits, and limited quantities of high-protein food. Typical tortoise diets include the following substrates:

Successfully caring for captive tortoises relies heavily on varying the diet. A shallow water dish should be provided to allow consumption, although caution should be taken not to overfill with water because the tortoise and box turtle cannot swim and will drown if submerged. The water should be changed daily because turtles may defecate in the water dish.

Sunlight or ultraviolet light should be provided to allow cholecalciferol (vitamin D) synthesis for shell formation and repair and to stimulate the appetite and basking behavior. Multivitamins containing vitamin D may be added to the diet every 1 to 2 weeks.

Aquatic turtles need a variety of food to achieve a balanced diet. The majority of the diet should be composed of whole animals, such as mice, earthworms, chopped goldfish or guppies, and slugs. Small amounts of insects, such as crickets, mealworms, flies, and grasshoppers, can also be offered. It is not recommended to feed such meats as hamburger or shellfish. Vegetables, such as dark leafy greens, cabbage, or romaine lettuce, can also be offered in small amounts. Commercial diets are available in floating stick forms, but keep in mind that supplementing with natural food, such as earthworms and small fish, is also recommended. Some tropical fish food can also be used to provide variation in diet. Note that aquatic turtles will only feed if they are in the water.

The most common nutritional deficiency in captive turtles is vitamin A deficiency. Clinical signs include respiratory infections, edematous eyes, urogenital tract obstructions, and beak overgrowths. Hypovitaminosis A can be prevented by providing the proper diet that supplies β-carotene, found in such food as earthworms, small fish, and green leafy vegetables. The most common clinical findings of sick turtles are due to anorexia and dehydration. Anorexia and dehydration are primarily husbandry related; causes include stress, a lack of food, an improper ambient temperature, improper diet, a parasitic infection, or metabolic disorders.