Dr. K. Sasikala*
Although both dogs and cats are classified as carnivores, their nutrient requirements are not identical. Dogs have the capability to use plant sources for synthesizing taurine, arachidonic acid, and vitamin A from their metabolic precursors present in plants, cysteine, linoleic acid and beta-carotene, respectively. Cats, bycontrast, either have diminished enzyme activities for synthesizing these nutrients (taurine and arachidonicacid) from their metabolic precursors, or they do not possess the enzyme. Cats must therefore obtain these nutrients from their diet.
GENERAL FEEDING RECOMMENDATIONS
Practitioners should advise clients to choose a commercial diet that has passed an Association of American Feed Control Officials (AAFCO) animal protocol test for the particular life stage of the cat or dog. The exception would be if a particular dog or cat has a medical problem; then a specific therapeutic diet should be fed.
MEETING ENERGY NEEDS
About 80% of the food eaten by mature cats and dogs is used to provide their energy needs. The requirements for protein, minerals, and vitamins can be met in the remaining dry matter. Therefore, meeting energy needs is the first consideration in feeding cats and dogs.
Energy, unlike individual amino acids, vitamins and minerals, is not supplied by any single nutrient but is provided by the oxidation of substrates, primarily fats, carbohydrates and proteins.
All adult cats and dogs that are voluntarily consuming food should be fed relative to their body condition and not by a formula.
Pregnancy causes a demand for energy greater than normal adult maintenance requirements. Queens and bitches in normal body condition may be given food free choice duringpregnancy to allow for the increase in body tissue that will be mobilized during lactation and by fetal energydemands.
Whereas the later stages of pregnancy increase energy requirements by about a third, lactation placesa huge demand on the bitch and queen and can result in energy intakes three to four times above maintenance.
PROTEINS AND AMINO ACIDS
Proteins are added to diets to provide essential amino acids and nitrogen. Both essential and dispensable amino acids are necessary at the cellular levelfor protein synthesis. Several amino acids are precursors for hormones and neurotransmitters.
Carnivores have no problem meeting their protein or amino acid requirements if they eat other animals,because the body composition of various animals is quite similar and is high in good-quality protein.
Nutritional problems arise only if a client attempts to feed a carnivore a vegetarian diet or a diet that haspoor-quality ingredients (e.g., by-products that are high in collagen, such as skin and bone) or productsthat have been excessively processed.
Specificamino acid deficiencies or excesses can cause a variety of problems, such as cataracts, dermatitis, hairloss or reddening of black hair or both, irritability, neurologic deficits, hyperammonemia, fatty liver, lowglutathione, and emesis.
MINERALS AND VITAMINS
Adult cats and dogs require the same minerals and vitamins that are essential to growing kittens and puppies.Although the requirements for growing kittens and puppies are fairly well defined, those for adults are not knownwith the same precision.
The bioavailability of calcium, phosphorus, and magnesium from plant sourcesis considerably less than that from mineral salts or bone and should be discounted by 50%.
In contrast, sodium,potassium, and chloride are readily exchangeable and no adjustments are necessary concerning their source.
Zinc deficiency is common in dogs fed some of the lower-quality dry diets.
Clinical signs of copper deficiency have been reported in newborn kittens fromqueens given diets containing copper oxide as a supplementary source of copper. Reproductive performance ofthe queens were also reduced.
Diagnosis of mineral deficiencies should be based on specific clinical signs, blood, plasma,or tissue concentrations for the species, as well as on reversal of clinical signs after supplementation with thespecific mineral while the cat or dog is maintained on the same diet.
For the fat-soluble vitamins A, D and E, the requirements are similar for adult cats and dogs. Cats, unlike dogs,are unable to use beta-carotene as a precursor for retinol, so they depend on preformed vitamin A in the diet.Neither cats nor dogs are capable of synthesizing vitamin D from ultraviolet (UV) light.
Requirements forvitamin E are a function of the total polyunsaturated fatty acids (PUFAs) in the diet. Because cats frequentlyconsume diets high in PUFAs, the requirement to prevent steatitis in cats is higher than that for dogs that aresubjected to lower dietary inputs of PUFAs.
Both cats and dogs have a metabolic requirement for vitamin K.Intestinal synthesis appears to be adequate to supply this need in dogs. When cats are fed some high-fish diets,they have a prolongation of clotting time and require supplemental vitamin K.
In contrast to the fat-soluble vitamins, the requirements for the water-soluble vitamins for cats versus dogs aredifferent.
Cats have a higher requirement than dogs for thiamine (vitamin B1) and are exposed to dietaryingredients that often contain both thiaminases (e.g., raw fish) and to canned diets that have sustained extensiveprocessing, causing loss of thiamine. As thiamine stores are rapidly exhausted, thiamine deficiency can readilyoccur in cats given deficient diets.
Cats, unlike dogs, are unable to use tryptophan as a precursor for niacinsynthesis, so niacin is an absolute essential dietary nutrient for cats.
Choline is often included among the “essential” vitamins because it supplies labile methyl groups.Methionine and betaine can also supply methyl groups. A lack of total methyl groups in the diet leads tofatty liver because of an inability to mobilize hepatic fat.
Taurine is synthesized de novo by dogs and cats from the sulfur amino acidscysteine and methionine.
The rate of taurine synthesis by cats is low; cats given a low-taurine diet are readily depleted of thisamino acid.
Taurine depletion is associated with a wide range of clinicalconditions, including feline central retinal degeneration, reversible dilated cardiomyopathy, reproductivefailure in queens, and developmental defects and growth retardation in kittens.
Until recently, diet-associated taurine deficiency in dogs has not been recognized. However, low bloodtaurine concentrations and dilated cardiomyopathy (DCM) have been identified in dogs that do not have agenetic predilection to this disease.
ESSENTIAL FATTY ACIDS
Dogs require two EFAs in the diet: linoleic acid and linolenic acid. In addition to linoleic and linolenic acids, cats undercertain conditions may require arachidonic acid, a member of the n-6 family of fatty acids in the diet.
A deficiency oflinoleic acid results in hyperkeratosis of skin, fatty degeneration of the liver and degeneration of thetestis. In addition, increased water loss through the skin occurs.
Clinical signs of arachidonate deficiency in cats are associated with eicosanoid dysfunction and includedefective reproduction in queens and changes in blood platelet aggregation.
A number of humanfoods such as alcohol, avocado, onions, garlic, chocolate, grapes, raisins, raw/ under cooked meat & eggs and xylitolcauseadverse effects in cats and dogs; thus thesehuman foods should not be fed to cats and dogs. Food faddism in human nutrition has resulted in malnutrition, toxicities and deficiencies. These same practices occur in dog and cat nutrition and should be avoided.
* Author is Assistant Professor, Department of Veterinary Clinical Medicine, Veterinary College and Research Institute, Namakkal- 637 002. Tamil Nadu Veterinary and Animal Sciences University, Tamil Nadu. Email: firstname.lastname@example.org