Introduction

Complete and balanced dog and cat foods, whether they come in the form of canned, dried, or a fresh-food diet, are known to promote health and wellness in dogs and cats. A growing appreciation for the role of diet in health and disease, as well as a number of highly publicized pet food recalls over the last decade, has many caregivers questioning the use of commercial pet foods to meet this end. Additionally, pet advice columns and pet food marketing companies have been guilty of using fear-based marketing to promote their foods or philosophies, often with little to know scientific support. These marketing tactics have stirred concerns and controversy over the use of certain ingredients, such as corn or wheat, and have caused some owners to become leery of manufacturers that incorporate these ingredients into their foods. Many owners, and some veterinarians, also advocate feeding dogs and cats home-prepared foods exclusively (raw or cooked, or both) and either cite perceived health benefits or a general mistrust of the pet food industry. It is important for veterinarians to understand the motivations, risks and benefits of each diet type to ensure that the nutritional needs of the individual animal are being met.

Dog and Cat Nutrient Basics

Whenever evaluating a new maintenance food for a dog or cat, it is important to ensure a complete and balanced intake of all essential nutrients are being provided, irrespective of the food form. Despite metabolic differences between dogs and cats, they have similar requirements for specific essential amino acids, essential long-chain fatty acids, macrominerals, trace minerals, water-soluble vitamins, and fat-soluble vitamins.¹ Both dogs and cats can synthesize vitamin C in the liver; neither species can synthesize vitamin D from UV exposure of skin; and both lack salivary amylase for the initial step in carbohydrate metabolism but have pancreatic amylases activity and glucose receptors on enterocytes for further carbohydrate digestion and absorption. Altogether dogs require about 37 essential nutrients in their diets and cats require 41 and it is important that the diet selected and fed on a regular basis meets these ongoing nutritional needs.

Commercial Diets

Complete and balanced commercial diets (dry, moist, pasteurized, cooked, or raw-meat based frozen or dehydrated) are designed to be fed as a sole source of nutrition to dogs and cats. The European Pet Food Industry Federation (FEDIF) and the Association of American Feed Control Officials (AAFCO) have established model guidelines for the countries and states regarding pet food labels, ingredient definitions, what can and cannot go into pet foods, and levels of specific essential nutrients required for a given life-stage.^2,3 Any pet food with an FEDIAF or AAFCO label of adequacy must have met these guidelines, though it is up to individual nations or states to regulate and enforce these recommendations. Commercial diets will then be labeled as having gone through “feeding trials” to ensure nutrient adequacy or as having been “formulated” to meet these requirements. Again, any commercial diet lacking a nutrition adequacy statement should be viewed with caution.

Home-Prepared Diets—Cooked & Raw

Home-prepared diets have grown in popularity over the last decade. For some pet owners it is in response to concerns about the production of commercial diets, for others feeding home-prepared foods reinforces the human-animal bond, and for still others a home-prepared diet is required to manage a medical condition.^4-6 Fresh meat whether it is fed raw or cooked is palatable to most dogs and cats, can be highly digestible, and depending on the cut of meat selected is higher in fat than most dry kibbles.⁷ The result is an animal that readily eats its food, has low stool volume, and a shiny coat and these direct visual features are often held up as “proof” of nutritional superiority to commercial canned or dry foods. Proponents of home-prepared foods claim that these diets are a safe and natural way to feed animals,⁸ but largely ignoring the potential negative consequences.

The detrimental aspects of raw meat diets in particular can be disastrous for the animal and the people in the household. Any raw meat ingredients can be a potential source of parasitic and bacterial exposure, which can include Neospora, Toxoplasma, Salmonella, E. coli, Campylobacter, and Cryptosporidium;^9-11 raw and cooked bones specifically carry a risk of gastrointestinal obstruction/perforation and oral trauma;^12,13 and are a poor source of essential minerals (such as calcium, phosphorus and magnesium) due to the poor digestibility of larger bones within the canine and feline digestive tract.¹⁴ Ultimately, the animal’s acceptance of a home-prepared diet does not change significantly when the meat is cooked or when more bioavailable sources of nutrients are used.

Published reviews of the nutritional adequacy of home-prepared (cooked and raw) diet recipes in recent years found that less than half of the recipes used by the pet owners provided a complete and balanced source of nutrients.^15-19 Most home-prepared diets for dogs and cats are lacking a sufficient source of calcium; a source of trace minerals (such as iodine, selenium, copper, and zinc); a source of linoleic acid; and a source of essential fat-soluble and water-soluble vitamins. While the perceived benefits of home-prepared diets are reinforced daily to the owner, nutrient deficiencies in adult animals are insidious and can lead to long-term complications, which can vary from poor skin and coat health to chronic diarrhea, osteopenia, anemia, altered drug metabolism, and hepatic lipidosis depending on the specific nutrients lacking in the diet.

Summary

Individual animals may vary in their response to specific commercially-available diets and there is no one diet-that-fits-all. If an owner elects to feed a home-prepared diet they should be counseled on the risks of this feeding strategy and cautioned that nutritionally-related disease can mimic other forms of chronic illness. Any animal eating a home-prepared diet should have at least an annual physical exam and health screening, including serum biochemistry (with T4), hematology and urinalysis profiles. While blood work and urinalysis results will give you a general overview of the animal’s health status, it will not pick-out specific deficiencies or excesses. A complete diet history (all foods and supplements) should be collected from the owner at each visit. Any home-prepared diet recipes should be obtained from a reputable, trained source. Additional resources, including a list of Board-certified Veterinary Nutritionists, can be found through the European Society of Veterinary & Comparative Nutrition (www.esvcn.eu) or American College of Veterinary Nutrition (www.acvn.org).

References

1.  Delaney SJ, Fascetti AJ. Basic nutrition overview. In: Fascetti, Delaney, eds. Applied Veterinary Clinical Nutrition, 1st ed. John Wiley & Sons, Ltd. 2012:9–22.

2.  European Pet Food Industry Federation. Nutrition Guidelines, July 2016. www.fediaf.org.

3.  Official Publication of the Association of American Feed Control Officials 2018. Oxford, IN: Association of American Feed Control Officials. 2018.

4.  Willoughby KN, et al. Feeding practices of dog and cat owners reflects attitudes about pet foods [abstract]. JAPAN. 2005;89:428.

5.  Roudebush P, Cowell CS. Results of hypoallergenic diet survey of veterinarians in North America with an evaluation of homemade diet prescriptions. Vet Dermatol. 1992;3:23–28.

6.  Wakefield LA, et al. Evaluation of cats fed vegetarian diets and attitudes of their caregivers. JAVMA. 2006;229:70–73.

7.  Vester BM, et al. Influence of feeding raw or extruded feline diets on nutrient digestibility and nitrogen metabolism of African wildcats (Felis lybica). Zoo Biology. 2010;29:676–686.

8.  Billinghurst I. Give Your Dog a Bone. The Practical and Common-Sense Way to Feed Your Dog. Alexandria, Australia: Bridge Printery;1993.

9.  Joffe DJ, Schlesinger DP. Preliminary assessment of the risk of Salmonella infection in dogs fed raw chicken diets. Can Vet J. 2002;43:441–442.

10.  Strohmeyer RA, et al. Evaluation of bacterial and protozoal contamination of commercially available raw meat diets for dogs. JAVMA. 2006;228(4):537–542.

11.  Lejeune JT, Hancock DD. Public health concerns associated with feeding raw meat diets to dogs. JAVMA. 2001;219(9):1222-1225.

12.  Frowde PE, et al. Oesophageal disease in 33 cats. J Fel Med Surg. 2011;13:564–596.

13.  Thompson HC, et al. Esophageal foreign bodies in dogs: 34 cases (2004–2009). JVECCS. 2012;22:253–261.

14.  Delay J, Laing J. Nutritional osteodystrophy in puppies fed a BARF diet. AHL Newsletter. 2002;6(2):23.

15.  Gray CM, et al. Nutritional adequacy of two vegan diets for cats. JAVMA. 2004;225(11):1670–1675.

16.  Lauten SD, et al. Computer analysis of nutrient sufficiency of published home-cooked diets for dogs and cats [abstract]. JVIM. 2005;19:476–477.

17.  Freeman LM, Michel KE. Evaluation of raw food diets for dogs. JAVMA. 2001;218(5):705–709.

18.  Larsen JA, et al. Evaluation of recipes for home-prepared diets for dogs and cats with chronic kidney disease. JAVMA. 2012;240:532–538.

19.  Heinze CR, et al. Assessment of commercial diets and recipes for home-prepared diets recommended for dogs with cancer. JAVMA. 2012;241:1453–1460.