Making Sense of Nutritional Trends

Maree Doolan, DVM, investigates the raw food diet trend, gives reason why owners may want to try it, and the current evidence about current pet food nutrition trends.

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As a clinician in a facility where vomiting and diarrhea top the list of presenting complaints, I find myself asking most clients “what does your pet eat?” It seems that more frequently the client will reply they are feeding some sort of grain-free, raw or other alternative diet. They are proud of the time, money and thought dedicated to the nutritional care of their pet. Meanwhile, I am becoming increasingly baffled by the growing number of dietary options and what they may offer (in terms of nutritional superiority) over more traditional ways of feeding our pets. I wonder how we can do better than “complete and balanced diets?” These foods are formulated to meet the standards set by the Association of American Feed Control Officials (AAFCO) with most high quality mainstream diets having undergone feeding trials to provide assurance that the food meets a dog's or a cat's requirement at each life stage1. I have always thought that pets do better than humans in terms of receiving excellent nutrition although are often left lacking when it comes to variety. In researching and writing this article, my goal was to try to gain an understanding of some of the benefits in feeding alternative diets, the owner’s motivation for taking this on as well as arguments we may have against them.

A quick Google search of the topic “raw and alternative veterinary diets” brings up a range of articles written defending alternative dietary choices and expressing anger and frustration at veterinary attitudes toward them. Some articles claim that veterinarians are not in a position to impartially advise on diet and nutrition given that much of our education in this area is sponsored by America’s leading pet food manufacturers2. There seems to be a belief that by advocating against raw food and other alternative diets, veterinarians may be trying to scare owners back to buying from the mainstream pet food industry3. In contrast, I believe as veterinarians, with our knowledge of gastrointestinal anatomy and physiology as well our ability to seek and critically evaluate information on the topic, that we are the most appropriate individuals to advise our clients regarding their pet’s nutritional needs.

Many pet owners feel that they can understand nutrition better than other fields in veterinary medicine. They may also be motivated to feed alternative diets because they feel that nutrition is one aspect of their pet's health they can control4. Other owners wish to feed their pets according to their own philosophical views, and may choose home prepared diets that are vegetarian, organic or raw5. There is an abundance of information readily available on the internet which serves to educate but can also lead to some false or misguided beliefs4.

As veterinarians, we are obligated to make recommendations based on sound clinical reasoning, scientific evidence, and an understanding of risk management. To further investigate the controversy, I searched several scientific databases. I found the articles on the topic of raw and alternative diets overwhelmingly negative. There is a plethora of scientific information available regarding the risk of infectious disease associated with raw diets6,7,8,9,10,11and nutritional inadequacy of many alternative diets9,11,12,13but little positive information.  Indeed, I was unable to find any statistically significant studies to provide evidence for claims of the nutritional superiority of raw, grain-free or homemade diets when fed as a maintenance diet to healthy pets.

Raw diets have become increasingly popular with advocates claiming benefits such as improved longevity to superior oral or general health and even disease resolution (especially gastrointestinal and immune-mediated disease)11.  One theory behind the raw food movement is that digestive enzymes found in fresh food enhance biological availability, whereas extreme heat (common to the preparation of commercial pet foods) leads to the depletion of enzymes and, therefore, depressed levels of digestible energy11.  Proponents cite literature that supports the idea that the enzymes can survive the digestive process in humans and may increase the nutritional value of food. This theory is extrapolated to explain why the same benefits may be achieved with our pets. There is, at this time, no statistically significant data to support this claim11.

On the negative side of the raw food debate, multiple case studies and articles demonstrate the risks of nutritional inadequacy (such as calcium imbalance) and infectious disease (due to Salmonella sp., E. Coli and other pathogens contaminating  raw food and the pet’s environment) 6,7,8,9,10,11.  In raw diets where feeding bones is advocated, the risk of creating gastrointestinal foreign body obstructions, breaking of teeth, and gut perforations is also documented14.

In 2012, the American Animal Hospital Association (AAHA) adopted a policy that does not endorse the feeding of raw protein sources explaining that there is overwhelming evidence that raw pet food diets risk animal and human health8. The position statement was endorsed by the American Association of Feline Practitioners and the National Association of State Public Health Veterinarians8. Despite this advisory, strong and passionate supporters of raw food diets continue to recommend and feed this type of commercially prepared or homemade food but mitigate the risk by stringently educating people in food preparation and hygiene practices as well as recommending against the diet in households with infants, the elderly and/or immune-compromised individuals14,15,16. It is recommended that nutritional adequacy of the diet is checked through regular monitoring, laboratory work and dietary analysis by a veterinary nutritionist11,14,15,16.

Grain-free dietary regimes are also becoming more popular among pet owners who may be lead to believe that grains are added to commercial diets as “fillers.” However, veterinary nutritionists argue that corn, oats, rice, barley, and other grains are actually healthy ingredients that contain protein, vitamins, and minerals16.  While there are a variety of reasons for recommending grain-free diets, it is important to remember that carbohydrates are not bad for all pets and that there have been no studies with evidence to suggest that feeding a food with a higher carbohydrate content will contribute to the development of conditions such as inflammatory bowel disease, urinary tract disease, diabetes mellitus or obesity4.

Home prepared diets (both cooked and raw) are also becoming more common and there seems to be many recipes for homemade pet diets available on the internet and in books. Benefits of home cooked diets include palatability, high digestibility, and ability to control exactly the ingredients and/or nutrient levels of the diet, thus tailoring to an individual pet’s needs14. The main risk with feeding home prepared meals is the potential for developing diseases related to nutrient imbalances such as nutritional secondary hyperparathyroidism, rickets, skin disease and anemia14.  The time and financial commitment required to ensure regular checkups and ongoing dietary formulation and analysis can be prohibitive and thus, feeding in this manner is not always practical11.

The common message I received when investigating alternative diets is that dietary advice is an important part of the veterinary consult and engaging the client in a dialogue regarding their dietary preferences can be valuable in growing the veterinary/client relationship.  For an increasing number of pet owners, preparing food is an important part of bonding and caring for their pet. Alternative diets may also help treat those pets that have specific dietary needs or intolerances. Through nutritional analysis, patient monitoring and education in food hygiene, risk posed by alternative diets can and should be mitigated. Current research indicates that the risks of feeding raw diets outweigh the possible benefits6,8,14. There are, however, many anecdotal reports touting the perceived improved health of animals receiving a raw food diet14. With so much interest in and controversy surrounding the issue, development of clinical trials and documentation of studies to support these claims are warranted. As with all clinical trials, there must be dedicated parties and financial backing to allow them to be developed and run. We may begin to see some significant studies as the raw and alternative diet industry develops more of a market share.


  1. Freeman , L. (2012) Answering Owners' Questions About Pet Foods.  Presented at the 64th Convention of the Canadian Veterinary Medical Association, Montreal, Quebec, Canada.
  2. “Myths about Raw Feeding.”  2007
  3. SF Gate “Raw food for pets? / Despite warnings by veterinarians, growing numbers of dog and cat owners are serving uncooked, homemade fare.” 2009
  4. Perea, S. (2010) Nutritional Myths & Fallacies: Talking to an Owner. Presented at ACVIM, Anaheim, California, USA.
  5. Larsen, J. (2011) Customized Home-Cooked Diets: Advantages of Working with a Veterinary Nutritionist. Presented at ACVIM, Denver, Colorado, USA.
  6. Schlessinger, D., Joffe, D.  Raw food diets in companion animals: A critical review.  Can Vet J. 2011; 52(1): 50–54.
  7. Weese, J., Rousseau, J., Arroyo, L.  Bacteriological evaluation of commercial canine and feline raw diets. Can Vet J. 2005; 46(6): 513-516.
  8. Cima, G.  AAHA warns about raw pet diet risks.  JAVMA news.  2012; 241(8): 980-1012.
  9. Baldwin, K., Bartges, J., Buffington, T.  AAHA nutritional assessment guidelines for dogs and cats.  J Am Anim Hosp Assoc. 2010; 46(4):285-96.
  10. FDA guidance for industry “Manufacture and labeling of raw meat foods for companion and captive noncompanion carnivores and omnivores.”  2004.
  11. Frequently asked Questions.  American College of Veterinary Nutrition.
  12. Hutchinson, D., Freeman, L., McCarthy, R., et al.  Seizures and severe nutrient deficiencies in a puppy fed a homemade diet.  JAVMA.  2012, 241(4): 477-483.
  13. Weeth, L.  Focus on nutrition: home-prepared diets for dogs and cats.  Compend Contin Educ Pract Vet. 2013; 35(3):E1-3.
  14. Villaverde, C. (2008) Alternative Nutrition: Assessing Home Cooked and Raw Diets. Presented at Canine Medicine Symposium, University of California, Davis, California, USA.
  15. Burns, K. (2012) Alternative and Raw food Diets. Presented at ACVIM, New Orleans, Louisiana, USA.
  16. Freeman , L. (2012) Talking to Owners About Unconventional Diets.  Presented at the 64th Convention of the Canadian Veterinary Medical Association, Montreal, Quebec, Canada.

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