Nutrition - Pros and Cons of Home-Prepared Diets for Cats and Dogs

By Malcolm Weir, DVM, MSc, MPH; Steve Marsden, DVM ND MSOM LAc DiplCH AHG, Shawn Messonnier, DVM and Cheryl Yuill, DVM, MSc, CVH

Cat licking raw foodAs a modern society, we understand the importance of food quality in maintaining or improving our health. We know that we need to eat good quality food in the appropriate quantity and balance for optimal health. Currently, questions are being raised about the nutritional choices we have been making for our pets, and whether they are appropriate.

In the 1940s, we began relying on pet food manufacturers to provide us with commercially prepared, conveniently packaged, and nutritionally complete and balanced foods for our pets. In the latter part of the twentieth century, a countermovement to shun this approach in favor of feeding more “natural” foods began to gain acceptance. Advocates of both approaches to feeding are equally convinced that their method is the best.

Do dogs and cats have special dietary requirements?

Cats are obligate carnivores, meaning they require meat as the primary component of their diet. Dogs are facultative carnivores and can fare well from a varied diet containing meats, grains, vegetables, grasses, etc. Because of their physiological differences, cats and dogs have specific requirements for certain essential amino acids (components of proteins) and other nutrients. For example, cats require a relatively high level of taurine compared to dogs to remain healthy.

“Cats are obligate carnivores, meaning they require meat as the primary component of their diet.”

Some people believe that the ideal food for a cat would be a raw, healthy mouse or bird, eaten in its entirety, and the ideal food for the average dog would be fresh whole prey, eaten raw and supplemented with whatever fresh grasses, fruits, and berries are in season. However, these choices can be socially unacceptable, impractical, and even dangerous for most of our pets. Our goal as caregivers to our pets is to provide the next-best choice.

The breed and function of an animal must be considered when selecting the optimal diet for it. Different breeds of dogs have been shown to have varying abilities to digest the same diet. Certain breeds that were developed in specific locations, such as arctic breeds (e.g., Siberian Husky, Samoyed, Alaskan Malamute) and some of the water breeds (e.g., Portuguese Water Dog, Barbet, English Setter) may have adapted to specialized diets that are common in their place of origin. Working pets (e.g., hunting dogs, field trial dogs, herding dogs, show cats) require different ratios of protein to fat in their diets than less active house pets. Inbreeding and genetic differences between individuals in each species may also result in a further need for specificity in the pet's diet in order to optimize health.

What are some of the benefits and drawbacks of commercial diets?

Without a doubt, a commercial diet is more convenient and enough has been learned about basic dietary requirements to prevent overt nutritional deficiencies. Some well-established or well-recognized pet food brands, especially 'premium' brands, have demonstrated this through feeding trials to ensure adequate nutrition. In these feeding trials, large groups of animals are fed a specific diet and are shown to remain healthy throughout the different stages of their lives.

Pet foods may contain ingredients of sub-optimal quality, and additives are frequently used to ensure a diet meets basic nutritional requirements. Processing can further degrade the nutrient quality of the food. Thus, manufacturers may add certain nutrients after processing to compensate for these losses.

"All pet foods must contain some form of preservatives in order to prolong shelf life."

All pet foods must contain some form of preservatives in order to prolong shelf life. Semi-moist formulas contain the highest levels of preservatives, followed next by dry diets (i.e., kibble). The process of canning minimizes the need for preservatives, so canned products usually contain the least preservatives. Products that are 'naturally-preserved' generally have a shorter shelf life than other products because natural preservatives, especially vitamin C and vitamin E, tend to oxidize or break down rapidly. Oxidation is accelerated by exposure to air once the package or container is opened, leading to rancidity or mold formation.

Pet food label highlighting AAFCO statement examplePet food formulas are based on macronutrient and micronutrient profiles recommended by organizations such as the Association of American Feed Control Officials (AAFCO). Nutrient profiles are meant to provide guidelines for adequate nutrition for an average healthy pet. These nutrient profiles may not be adequate in all cases since they, in turn, were developed from National Research Council guidelines. These guidelines assume complete bioavailability (the proportion that is digested and absorbed) of the nutrients and leave no margin of error for breed differences, impaired absorption, reduced digestibility of certain foodstuffs, or changes in animal physiology in certain disease states.

"Nutrient profiles are meant to provide guidelines for adequate nutrition for an average healthy pet."

Even adequate macronutrient and micronutrient levels may not guarantee nutritional adequacy. Nutraceuticals, which serve as co-factors and components of essential biochemical processes, are not considered in the formation of nutritional guidelines. Some holistic practitioners recommend that pets fed a diet of commercial food should receive supplemental meats and vegetables to provide nutrients that have yet to be recognized as essential components of the carnivorous diet.

Recent concerns have been raised about feeding dry foods to cats. Dry foods are often fed in a free-choice manner, which may lead to obesity due to the overconsumption of grains (source of carbohydrates). There are concerns that carbohydrate excess in a cat’s diet may predispose it to diabetes mellitus. In addition, if a cat is fed an exclusively dry diet and does not drink enough water on a regular basis, urinary problems such as crystals may develop as a result of more highly concentrated urine.

What do I need to know about pet food labels?

"At the present time, pet food labels are only required to show a chemical analysis, which does not necessarily equate to nutrient availability."

At the present time, pet food labels are only required to show a chemical analysis, which does not necessarily equate to nutrient bioavailability. For example, hair, skin, muscle meat, and soybeans are all composed primarily of protein but differ in quality and digestibility. Additionally, a label that claims “no preservatives added” does not mean the food contains no preservatives, but merely that the manufacturer did not add any. Preservatives may still have been added by a manufacturer's suppliers. To avoid preservatives, look for a label that states “preservative-free.” A preservative-free food will often have an extremely short shelf life unless it is kept frozen.

What are the benefits of feeding a home-prepared diet?

Those who support home-prepared diets for pets typically emphasize the importance of providing a variety of fresh whole foods for the maintenance of good health.

The benefits of home-prepared diets include the pet owner’s confidence in the freshness and wholesomeness of the ingredients (especially if using organic ingredients) as well as the potential inclusion of non-essential or synergistic components such as nutraceuticals in the diet. Many dogs and cats may have improved skin and coat conditions and/or increased levels of energy when fed a quality home-prepared diet. The exception to this is the pet with pre-existing allergies to one or more components of the diet.

What should I know about feeding a home-prepared diet to my pet?

Home-prepared diets must be adequately balanced to maintain health. The optimal way to avoid nutritional deficiencies and excesses is to follow diet recipes formulated by veterinary nutritionists or that otherwise at least meet the basic nutritional requirements for the species. To avoid trace nutrient deficiencies or excesses, it is recommended to vary each diet component. Consider using different proteins, vegetables, and grains with each batch of food. Caution should be exercised, however, because the nutrient composition of different components may vary significantly. Some recipes will provide appropriate substitution quantities to facilitate varying the recipe.

" is absolutely necessary to provide supplemental calcium in all home prepared pet diets."

Because meats and many vegetables are deficient in calcium, it is absolutely necessary to provide supplemental calcium in all home-prepared diets. Most diet recipes include vitamin and mineral supplements. If the food is cooked and these supplements are added before or during the cooking process, they may become denatured or inactivated. This is a particular problem with some vitamins.

What are the risks of feeding a home-prepared diet to my pet?

The ratios of individual dietary components in different recipes will vary considerably and adhering to one recipe exclusively may cause severe nutritional imbalances. Avoid recipes that are complicated or time-consuming to prepare, to prevent the desire for shortcuts in preparation. Simply feeding a diet of table scraps or a mixture of meat, grains, and vegetables into a bowl could cause malnourishment in a pet.

Golden Retriever puppy with its motherProblems may occur if a pet's diet is either under or over supplemented with certain vitamins and minerals. The most common imbalances in home-prepared diets involve calcium, phosphorus, zinc, magnesium, and iron. Animals with increased nutritional needs associated with growth or reproduction have different requirements for energy and nutrients and require enhanced protein levels and optimal ratios of vitamins and minerals to support growth. The advice of a veterinarian with advanced nutritional knowledge, or a veterinary nutritionist, is imperative to decrease these avoidable risks to the pet's well-being.

"...even healthy animals can shed pathogenic bacteria in their feces, possibly presenting a health risk to their human companions."

Some popular authors of pet diets recommend feeding grain-free (or carbohydrate-free) diets, raw meat diets, or raw food and raw bone diets. However, animals with compromised health may be susceptible to illness caused by the bacterial pathogens potentially found in raw diets and even healthy animals can shed pathogenic bacteria in their feces, possibly presenting a health risk to their human companions.

Raw bones may be okay in a diet, depending on the size of the pet being fed and the size of the bone. An inappropriate bone size, however, may cause intestinal complications such as an obstruction or perforation. Cooked bones must NEVER be fed to pets because they are brittle and prone to splintering, which can cause both obstructions and perforations of the intestinal tract.

How can I minimize the risks associated with home-prepared diets?

Discuss your pet's diet candidly with your veterinarian, including any treats or supplements that you provide. Have your pet examined regularly so that any early indicators of medical problems may be detected. Since animals age more rapidly than humans, a good rule of thumb is to have a complete physical examination every six months. In addition to a physical examination, it is prudent to have a biochemical analysis and complete blood count conducted on your pet's blood at these intervals. Periodic radiographs to assess bone density and structure, as well as tissue density, can also assist in detecting overt mineral imbalances, such as a calcium deficiency.

What symptoms or conditions may be treated with home-prepared diets?

Symptoms such as excessive shedding, itching, skin lesions, and digestive disturbances have been correlated with allergies or sensitivities to components of commercial diets, or to the nutritional inadequacy of the diet for a specific individual or breed. Conditions related to insulin resistance, such as type II diabetes mellitus, may respond dramatically to a low carbohydrate diet, especially in cats. Animals with specific dietary needs or health problems may show dramatic improvement in their state of health when fed a home-prepared diet that has been nutritionally formulated to meet these needs.

Remember to always consult with a veterinary nutritionist to ensure the diet is balanced and complete.

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