Nutritional Requirements of Dogs and Cats

Nutritional Requirements of Dogs and Cats

The nutritional needs of dogs and cats can be satisfied in a variety of ways through the use of commercially available diets. Fortunately, there is no need for pet owners to become nutritional specialist to provide good nutrition to their pet.

You can choose from hundreds of brands of pet food to achieve optimum nutrient intake, both economically and conveniently. Furthermore, nutritional information is relatively abundant from manufacturers of pet foods in both published literature and advertising.

Estimation of the requirements can be complicated by the wide variation in size, performance, physical exertion, reproduction, age, environmental and psychological
stress, etc. Yet, there is shortage of information on definitive nutrient requirements related to breeds, age and sex.

Even with some suggested requirements, a substantial variation exists, which is not really surprising considering those factors plus breed diversity, especially in canine species.

Therefore, the requirements cannot be defined simply as being at a single level, but rather should be given as a range. Optimum nutrition often requires nutrients above the minimum requirements and the final determination must be based on pet’s response to a particular feeding regimen.


While often overlooked, water is of utmost importance and dehydration is a primary concern in growing puppies and kittens because of their high body water content.

Water can be provided by the moisture content of food, metabolic water and drinking water:

  • Water content of commercial diets can range form 10% to 78%, therefore the consumption of water would vary accordingly.
  • In general, a dog gets about 25% of the requirements from drinking water, but a cat gets only 10% from drinking water.


Energy needs of dogs and cats:

  • Energy needs are affected by the animal’s metabolic efficiency, environmental factors, physical exercise and activity level, age and the stage of production.
  • The energy needs per unit of body weight decreases as the size of the animal increases, just like any other warm-blooded animals.

Animals fed a balanced diet tend to eat to satisfy their energy need, therefore diets can be compared in terms of a nutrient per unit of energy.


Grain starches provide an important and economical source of dietary energy in most pet foods. There is limited information on this area, but a dog can utilize up to 65% – 70% dietary carbohydrates, whereas a cat can utilize only about 35% – 40%. Whereas cats have active hexokinase but not glucokinase, dogs have both.


  • Inclusion of small amounts of fiber is necessary for the normal function of the GI tract by providing the bulk, maintaining normal passage rate and intestinal motility and maintaining the structural integrity of gastrointestinal mucosa.
  • Common sources of fiber include wheat middlings, citrus, beet pulp, soy hulls, peanut hulls, etc. Also, grains and plant protein sources can contribute fibers.
  • Fermentation of fiber (i.e. VFA) may contribute as energy source for the cells lining the intestine.
  • Certain types of fiber (e.g. fructooligosaccharides) may be beneficial in the treatment of some gastrointestinal diseases.
  • Just like other nonruminant species, too much fiber can have some adverse effects.


In pet foods, fat serves as a concentrated form of energy, a carrier for fat-soluble vitamins, a source of essential fatty acids and an enhancer of diet palatability.

The optimum content of lipids depends on other nutrients and can be as low as 5% – 10% in low-CP or inferior-quality protein, but can increase concomitantly with the increase in the CP and / or protein quality.

Dogs and cats need linoleic acid and cats also need arachidonic acid because they don’t have appropriate enzymes to convert linoleic to arachidonic acid.

Common sources of lipids are tallow, lard, poultry fat and many vegetable oils. Animal sources, particularly fish oil, are appropriate source of arachidonic acid, but not plant sources.

A proper proportion of Omega-3 and Omega-6 two may have beneficial effects on some disorders, such as treatment of allergic skin disorders in dogs, according to
some studies.

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Ideally, an intact protein source would supply all 10 indispensable amino acids in adequate amounts, however there are considerable variations in the protein quality among various sources.

Furthermore, relatively little is known about the quantitative amino acid requirements for canines and felines and the factors affecting these requirements. Some studies have led to the quantitative assessment of amino acid requirements and the resulting minimum requirements were incorporated into the NRC guidelines. As those were the minimums established with purified diets, the AAFCO Nutrient Profiles has added some safety margins.

Plant protein sources, such as soybean meal and corn gluten meal and animal protein sources, such as poultry, meat and respective byproducts, are common ingredients in pet foods.

Although cereals are a major source of energy in cereal-based products, they also supply a substantial portion of protein. Often, those are deficient in some indispensable amino acids, so fresh meats, meat and poultry meals and various meat byproducts are often added to alleviate that deficiency.

As in other nonruminant species, the indispensable amino acid requirements are affected by the age, sex and breed / genetic potential of the animal:

  • Young puppies may not be affected by sex, but the Lys requirement is higher for the immature male Beagle vs. the immature female.
  • Labradors may have higher S-amino acid needs than beagles, and also S-amino acid needs of pointer puppies are different from Beagles or Labradors.

Cats, strict carnivores, are unique in their protein / amino acid needs and have substantially higher requirements than dogs because of the high activity of the amino acid catabolic enzymes in the liver.

That may not be of a practical importance, but cats are very sensitive to a deficiency of Arg, which can lead to hyperammonemia in less than an hour.

Cats also have higher S-amino acid needs, relative to other mammals because of the needs for the cat’s thick hair coat, which is high in cysteine.

The amino acid taurine is uniquely important for cats. Taurine is synthesized from Met and Cys in the liver and other tissues and the amount synthesized is sufficient in dogs but not in cats. Taurine is present in bile as taurocholic acid and in high concentrations in the retina and olfactory bulb.

Unlike the dog, the cat conjugates cholic acid exclusively with taurine and is unable to alternate between taurine and glycine conjugations in the production of bile:

  • That can lead to a reduction in conjugated bile acids and central retinal degeneration can develop.
  • Typically, reduced visual acuity, without total loss of vision, has been seen in older kittens and adult cats.
  • It may also be associated with cardiomyopathy and poor reproductive performance.

Therefore, the cat has a continual dietary need for taurine, which is only present in animal protein sources.

Vitamins and Minerals


A high-quality fat source should be used to ensure fat-soluble vitamin absorption. Many diets add an antioxidant.

Water-soluble vitamins are carefully selected and added in excess of minimum needs to compensate for losses associated with heat processing and extended shelf life.

Conversion of β-carotene to vitamin A in cats:

  • It cannot convert because of a deficiency of the intestinal enzyme, ββ-carotene-15-15′-dioxigenase, so they need dietary source of preformed vitamin A.
  • Furthermore, cats may be susceptible to vitamin A toxicity because of no regulation at the intestinal mucosa.

Cats have a unique dietary need for niacin because they cannot synthesize it from Trp.


There is shortage of information on quantitative and qualitative mineral requirements for dogs and cats. To ensure dietary adequacy, pet foods are fortified with essential minerals.

The proper ratio of Ca to P is about 1.2:1 (1:1 for cats and 1.2:1 to 1.4:1 for dogs). Common sources of Ca are bone meal, skim milk and alfalfa leaf meal, whereas bone meal and meat scraps can supply P. Vitamin D is needed for the utilization of Ca and P.

Many dog owners feel that growing puppies need additional Ca to prevent skeletal problems, however supplementing previously adequate diet with Ca may have no beneficial effect and actually it may have some adverse effects.

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Commercial Pet Foods and Table Scraps

Dry Pet Foods

This is the most common type of pet food in the U.S. Dry pet food commonly contains whole or dehulled cereal grains, cereal byproducts, soybean products, animal products, milk products, fat and oils and mineral and vitamin supplements.

Cereals are heat-treated to dextrinize starches and improve their digestibility.

Enough fats are added to increase the energy density and adequate amounts of vitamins and minerals are carefully blended throughout the meat and cereal mixture. Most mixtures contain about 6% to 10% moisture and the average energy value is 1,500 to 1,600 kcal / lb or 300 to 400 kca1 / 8 oz cup.

There are three main types of dry foods:

  • Dry meals. These may be pelleted or pelleted and then crumbled to a uniform particle size. Alternatively, they may be fat-coated, which increases their energy density and enhances the palatability.
  • Kibbles. These are ground together cereal grains and dried meat scraps, along with dairy products, vitamins and minerals into a flour, blended with water and formed into a dough. Kibbles may be baked on a large sheet and then crumbled or “kibbled” into uniform-sized fragments.
  • Expanded dry foods. These are made by mixing raw grains, meat meal, vegetables, dairy products, vitamins and minerals with steam inside a blending pressure cooker, which allows the ingredients to be cooked while being whipped into a homogeneous mixture. The mixture would be pushed through a die and expanded with steam and air into small porous nuggets, which are hardened by passing through heated air streams. Then the hardened nugget is usually passed through a spray chamber and coated with a liquid fat, carbohydrate or milk product to provides additional energy or palatability.
Semimoist Foods

These represent a very diverse group of products and are very convenient to feed, but have fallen in popularity in recent years. There is, however, an increase in the variety of semimoist “treats and snacks”.

The moisture content is about 23% to 40% and generally contains a mixture of soybean meal, corn syrup, fresh meat or meat by-products, animal fat, vitamins and minerals, together with preservatives and humectants.

Phosphoric, hydrochloric and malic acids are commonly used acids to lower the pH to retard bacterial growth and spoilage. Sugars, corn syrup and salts elevate the soluble solids in the product and bind the water so it is unavailable to bacteria and fungi.

Propylene glycol is hygroscopic and binds moisture in the product to keep the food pliable and prevent drying, but has been banned by the FDA to use as a humectant because of potential risk to cats.

Commonly packaged with cellophane or foil in portion-controlled servings, semimoist food can be stored unrefrigerated because of the preservatives and humectants. It is often shaped and colored to resemble meat chunks or hamburger patties.

Canned Foods

These are extremely popular, especially for cats. The canned cat food market has grown dramatically in recent years.

Fresh, wet ingredients are sealed into containers (generally cans) to prevent any recontamination and then subjected to a heat- sterilization process to destroy any
microorganisms of spoilage already in the food.

Types of canned foods:

  • Ration-type canned foods. Ground fresh meat and meat byproducts along with fat, water and cereal ingredients are blended to make a complete balanced diet.
  • Gourmet or meat-type canned foods. These look like containing a substantial amount of meat, but actually contain a variety of animal byproducts and textured vegetable protein, which is composed of extruded soy flour mixed with red or brown coloring. The high protein content requires the animal to use protein as its major energy source.

    Because of their high protein and fat content and high palatability, these are excellent to feed when food intake is decreased because of anorexia from any cause and when protein requirements are increased (e.g. for extensive wound healing and protein losing nephropathy or enteropathy).

    The gourmet canned cat foods are made to be extremely palatable and feature a good diet to try to induce voluntary food intake in either the anorectic dog or cat. They are composed primarily of animal tissues such as shrimp, tuna, kidney, liver and chicken, in numerous combinations.

    Table Scraps

    These are frequently quite palatable to dogs but generally not nutritionally balanced. Most table scraps consist of fats and carbohydrates, thus yielding lots of energy and little else.

    The dog may obtain a sizeable portion of its daily energy need from the useless scraps and lose appetite for the commercial food.

    Spicy food should not be given to any animal.

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    Image credit: Wikimedia.



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