Regarding the AVMA Policy on Raw or Undercooked Animal-Source Protein in Cat and Dog Diets (by James K. Russell, Ph. D.)
The executive board of the American Veterinary Medical Association has recently proposed a policy statement on the provision of raw and undercooked diets to cats and dogs. Publication of the policy is pending general approval by the association.
The policy is generally sensible, but risks being misconstrued. Further, while it cites a number of scientific studies, they are of mixed quality and none fully settle the principal concern addressed by the policy—the safety regarding raw meat ingredients for consumption in companion animals and for food handlers (typically their owners). In response to public concern, the association explains that it is not in a position to effect a ban, not having any governmental authority. Nonetheless, policies of non-profit professional societies can be highly influential. In the medical community, it is understood that this influence is consequential, and expected that the process behind policy development be transparent. It cannot be ignored that the prepared dog food industry, with over $10 billion in annual revenues[i], has a stake in policies potentially affecting the prevalence of alternative diets. It does not seem too much to ask that any potential conflict of interest on the part of the authors with respect to the industry should be disclosed.
Here is the policy, in short:
- Never feed inadequately treated animal-source protein to cats and dogs
- Restrict cats' and dogs' access to carrion and animal carcasses (e.g. while hunting)
-Provide fresh, clean, nutritionally balanced and complete commercially prepared or home-cooked food to cats and dogs, and dispose of uneaten food at least daily
-Practice personal hygiene (e.g. handwashing) before and after feeding cats and dogs, providing treats, cleaning pet dishes, and disposing of uneaten food
Of course practicing good hygiene with our pets makes good sense, as does the provision of clean, nutritious food and the disposal of uneaten food. Access to carcasses is not a major issue for most pet owners. Given the topic of the policy, and its position, most attention will focus on the first statement:
"Never feed inadequately treated animal-source protein to cats and dogs".
Depending on how it is interpreted, this statement is at best unclear, and under a broad interpretation goes beyond the available evidence. Read most straightforwardly, it amounts to a recommendation to never feed raw meat and eggs to our carnivore pets. Such a recommendation is not well supported by the evidence. An alternative reading would permit raw meats and eggs that were "adequately treated". Whether adequate treatment is consistent with maintenance of food in a raw condition is unclear, and the policy does not speak to this point. Certainly, it is established human practice to carefully treat raw animal protein safely while retaining its rawness - this is true for instance of sushi, sashimi and steak tartare, not to mention salad. And, it is recognized that particular care is required when preparing raw foods for human consumption because of the heightened risk of bacterial contamination. Cooking is an easy and reliable method for protecting against bacterial contamination; however, it is not the only effective method.
Few of the studies cited in support of the policy include controls and several are little more than anecdotal. Most of the studies advocate good hygienic practices when preparing raw meat meals, as do statements from the U.S. Dept. of Agriculture Food Safety and Inspection Service, from the U.S. Food and Drug Administration, and from the U.S. Centers for Disease Control and Prevention. A representative list of optimal hygienic measures would include[ii],[iii],[iv],[v],[vi]:
- use of only meats inspected (e.g. by USDA) and found suitable for human consumption
- hand washing after handling raw foods
- regular washing or disinfection with a mild bleach solution of bowls, food preparation surfaces and implements
- avoidance of cross-contamination by use of separate preparation surfaces for separate ingredients
- proper storage of raw ingredients in the refrigerator or, for extended periods, the freezer
- disposal of unconsumed meal portions
-avoidance of exposure of young children, the elderly or the ill to raw food ingredients
Unfortunately, not one of the studies cited in support of the policy has included any steps to ensure these good practices are maintained in the study participants. Food sources are characterized only to the level of species (beef, chicken, turkey, ...), if at all. Inspection status regarding fitness for human consumption is not stated in a single study. Descriptions of methods are restricted to the methods of handling for fecal samples with no mention of food preparation methods or hygienic measures in homes or manufacturing facilities. Furthermore, no study cited in support of the AVMA policy included any control samples from commercially available meals prepared by standard methods (cooking, extrusion). Even the authors of the most extensive and methodologically sound of these studies[ii] acknowledged, "There is currently inadequate information regarding the safety of raw diets in terms of both animal and human disease." One study[vii] cited in support of the recently stated policy of Pet Partners to preclude animals fed raw diets from participation in animal therapy programs that involve hospital visitation did include limited canned and extruded products as controls. The finding suggested higher incidence of bacterial contamination in commercially available raw diets than in these more standard commercially available diets, but notably contamination was found in diets of all types. While it was one of the most rigorous studies in this area, it was not sufficiently powered statistically to prove this point to a scientific standard. As the authors noted in the study, "a limited number of samples of the dry and canned diets were included as controls, and this did not allow for statistical analyses or comparisons. Further investigation is warranted to make quantitative comparisons of the degree of bacterial contamination among those types of commercial diets." The broad finding of contamination in all diets reflect, in part the coarseness of the methods for detecting bacteria. In practice, the bacteria of greatest concern for human health are Escherichia coli O157:H7, one of hundreds of variants of E. coli, and a handful of serovars of Salmonella enterica enterica, out of thousands of serovars. This study and others have tested only for the presence or absence of E. coli-like bacteria or Salmonella species—not for species specific variants that are risk factors for clinical disease. Salmonella is an important but particularly common bacterial food contaminant, the basis for recent recalls of commercial dog food[viii], as well as of eggs, spinach and alfalfa sprouts, among other human foods. Because they are relevant human pathogens, several of the studies cited by the AVMA and Pet Partners policies also tested for Camplylobacter spp., Clostridium spp. and methicillin-resistant Staphylococcus aureus (MRSA)ii,[ix]. No relationship of any of these specifically pathogenic varieties of species and the use of raw food diets was found.
It is understandable that scientific research has yet to provide all the necessary answers for this somewhat contentious issue, which has emerged relatively recently. To be fair, scientific evidence for the benefits of raw food diets is limited as well, but it is important to recognize that this is the state of our understanding. Declarative policies should not close the door on practices without good evidence solely because they are relatively unfamiliar. It is not constructive to indiscriminately cite parades of bacteriological and parasiticological horrors to a public audience ill-prepared to evaluate them. For instance, one study cited in support of the AVMA policy described essentially every known pathogen of dogs, without any assessment of clinical or for that matter canine relevance.[x] Describing the risk of feeding everything from muskrat to walrus to pets is really more confusing than helpful, and discussion of anthrax, botulism and tuberculosis is little short of alarmist.
Good studies of practical raw meat diets representative of use by pet owners, prepared and presented with good, well-documented methods and including appropriate controls remain to be done. It is too early, on the basis of present evidence, to conclude that raw food diets properly handled are particularly risky, and to be fair it is too early to conclude that they are not. Good studies are called for.
There is legitimate basis for concern regarding bacterial contamination of raw meat and eggs. In the interim, it makes sense to practice good hygienic methods, use well-inspected ingredients, handle them carefully, and avoid contact of raw foods and food preparation materials by the very young, the very old and the ill. The evidence is not conclusive, but particular caution being warranted under the circumstances, the decision of Pet Partners to avoid raw diets in therapy animals working in hospitals seems sensible until more conclusive evidence is available.
Apart from the particular care due the infirm, it is reasonable to keep in mind that "no confirmed cases of human salmonellosis have been associated with these diets"[xi]
As for the AVMA policy, it is only reasonable if the first statement "Never feed inadequately treated animal-source protein to cats and dogs" is permissive of an interpretation that careful hygienic methods constitute adequate treatment. A blanket ban of raw food no matter how prepared and handled is unwarranted by the scientific evidence.
A recent review[xii] of the evidence surrounding raw food diets on the basis of standards of evidence conventionally used in medicine concluded: "Although there is a lack of large cohort studies to evaluate risk or benefit of raw meat diets fed to pets, there is enough evidence to compel veterinarians to discuss human health implications of these diets with owners." This is sensible advice. The evidence does not currently warrant a policy that may be interpreted as tantamount to a ban. All those interested in the safety and efficacy of raw food diets for pets should keep their minds open, and support the further research that will be required for better understanding of the risks and benefits of raw foods.
James K. Russell, Ph. D.