Introduction

In recent years there has been great interest by pet owners to feed unconventional diets to their pets. Most people claim that their primary interest is to improve the health of their animal, which they feel is not accomplished by using conventional commercial diets. Effective propaganda campaigns have swayed thousands of owners to question manufacturing practices of the pet food industry and to seek alternatives. Unfortunately, information substantiating claims by the proponents of such diets is lacking. All food processing is being viewed as harmful and all things natural are viewed as beneficial. With greater acceptance in these types of diets, veterinarians need to be aware of the important issues surrounding this controversial topic and in particular the implications and risks this practice has to critically hospitalized critically ill animals in an ICU setting. The purpose of this lecture is to present some of the concerns regarding raw food diets and other unconventional diets and highlight any evidence regarding the use of such diets.

Why Is This Approach Gaining Acceptance?

Use of raw foods and other unconventional diets is obviously filling a niche not addressed by conventional pet food companies. There is a perception (mostly propagated by proponents of unconventional diets) that processing of pet foods is the cause of many ailments seen in the pet population. Conspiracy theories linking pet food industry and the veterinary profession are particularly interesting allegations. As an all-natural alternative, diets such as a Bones and Raw Food (BARF) appeal to those suspicious of the pet food industry (and of the veterinary profession). A group that quite readily accepted such notions was dog and cat breeders, who hold a great deal of influence over prospective pet owners. With the endorsement from many breeders, the movement to feed raw foods to companion animals gained a great deal of momentum. As new pet owners invariably receive the majority of advice on raising dogs solely from breeders, veterinarians are often left out of important decision-making such as choosing an appropriate diet.

Where Did This Trend Originate?

When one investigates the claims why raw food diets are ‘superior,’ a common cited reason is that dogs “were designed to eat raw food.” From the types of teeth they have, to their evolutionary links, much of the justification of feeding raw food stems from the belief that dogs are healthier when fed as if they were “still in the wild.” Leaving the issue of domestication aside, the notion that wild canids somehow were in ideal nutritional status when fed raw food is certainly unfounded. In fact, archaeological data suggests that prehistoric canids were omnivores and not pure carnivores. Modern wolves (which are often misrepresented as the reference species for domestic dogs) have evolved to consume prey mostly because of human encroachment in their habitats. So, in reality, domestication of dogs not only introduced the dependence by dogs on humans for food, it also led to the changes in diets of wild canids. Domestication of both dogs and cats has resulted in remarkable prolongation and improvement in the quality of life for many animals, and many of the benefits could be directly linked with the provision of balanced and complete commercial diets. While improvements in food palatability have probably contributed to the onset of obesity and associated conditions, consistent use of balanced commercial diets has reversed malnutrition in many more patients.

What Are the Concerns?

In order to truly offer a balanced and informed analysis of the evidence on the potential risks and benefits of feeding raw meat-based diets would require the availability of data from high quality studies. Unfortunately, there is very little data available to formulate a balanced analysis. Much of the information used to support one view or another on the merits and dangers of feeding raw meat-based diets are based on low quality studies composed of anecdotal reports, case reports, and case-series. On the major issue of safety related to bacterial contamination, the evidence is more robust and more numerous, but comparative studies on the impact on the health of animals that consume raw meat-based diets are still lacking.

A particularly dangerous notion is that raw meat-based diets somehow pose no health risk because animals are “resistant to such infections.” While it is true that there may be a reduced risk, by no means are dogs immune to systemic infections due to enteric bacteria such as Salmonella and Campylobacter. In fact, dogs and cats with chronic or acute diarrhoea are commonly evaluated for Salmonella and Campylobacter infections. We know that dogs and cats can be severely affected by salmonellosis and Campylobacter infections. But even if one accepts that many dogs and cats can consume contaminated raw-food diets and not become overtly ill, this is not to say they don’t pose a risk to others. In experimental studies, dogs fed Salmonella-contaminated food reliably shed Salmonella for many days without showing any gastrointestinal signs. The fact that many asymptomatic dogs can shed Salmonella into the environment while appearing healthy has led to banning dogs that are fed raw-meat diets from being used as therapy dogs in some areas. There are also studies that have shown that a rise in cases of Salmonella in infants (some which are multi-drug resistant) could be traced to raw hide treats given to dogs. Recently, the FDA undertook a 2-year study evaluating the microbial contamination of conventional commercial pet foods in comparison to commercial raw-foods which showed the much higher risk of incidence of coliform and Listeria spp. in commercial raw-meat foods. But perhaps most worrisome of all comes from a study evaluating a large group of healthy Labradors that were not in any way exposed to veterinary hospitals or treated with any antibiotics (i.e., lack of selection pressure associated with antimicrobial use). In these healthy dogs, not only was there a presence of clinically-relevant organisms isolated from these dogs, but also many harboured multi-drug resistant bacteria. Investigators also identified that the major factor in increasing the likelihood of having these bacteria was being fed a raw-meat based diet. The major significance of this study was that the profile of community bacterial colonization (i.e., without selection pressures associated with antimicrobial use or contact with veterinary hospitals) is changing to reflect multi-drug resistant bacterial populations and is occurring due to feeding of raw-meat based diets. The obvious question (which has not been thus far investigated) is what risk do such animals that are fed raw-meat based diets pose to other animals in veterinary hospitals when they are hospitalized themselves? The most rational conclusion is that veterinary hospitals must perform a risk assessment about hospitalizing animals normally fed raw-meat based diets at home. Does your hospital accept such raw-meat based diets to be fed while the animal is hospitalized? And knowing that such animals could be shedding multi-drug resistant bacteria, including Salmonella and Campylobacter, what is your hospital policy for handling these animals? Should they be in isolation similarly to dogs and cats with other contagious infectious diseases? Until we have more direct evidence to the contrary, it would seem sensible to ban feeding raw meat-based diets in hospital settings (especially ICUs) and that if animals normally fed in this manner are hospitalized, that barrier nursing protocols should be instituted.

Implications for ICU Patients

As already alluded to, the major concern with feeding raw meat-based diet centres on bacterial contamination of the diet and the risk posed to the animals fed in this manner, their owners, and to other hospitalized patients. As many ICU patients are already immune-compromised, having animals that may be shedding virulent and multi-drug resistant bacteria in the ICU environment must be addressed by the hospital. Hospitals should have established policies and protocols for dealing with such cases. In the author’s institution, there is a strict policy that no animal is to be fed raw foods and that whenever these animals are hospitalized, that barrier nursing protocols are instituted in the care of such patients (e.g., disposable protective clothing, gloves). All healthcare staff that comes in contact with such patients must adhere to good hygiene practice and all areas of the hospital that such patients come in contact with must be appropriately disinfected. Whether such animals must have mandatory screening for Salmonella or multi-drug resistant bacteria is unknown at this point and each hospital should consider what should be done. It is also unknown if such animals should be isolated rather than barrier nursed, however, animals that require intensive care would be potentially compromised if cared for in isolation facilities. Another consideration is that the number of animals being fed raw-meat based diets will likely escalate and it would be unfeasible to manage all of such patients in isolation.

Summary

Given the absolute and passionate devotion to the practice of feeding raw meat-based diets demonstrated by many pet owners, breeders, and even veterinarians, it is safe to say that this way of feeding is here to stay. Despite growing evidence highlighting the possible dangers to both animals fed such diets and public health concerns amongst those that feed these diets, many are swayed by the appeal of feeding a “natural diet.” It is probably worth noting that growing scientific knowledge highlighting possible or likely dangers will not necessarily influence a segment of pet owners because “scientific evidence” is not what guides their relationship with their pets. Veterinarians should not lose sight of this. Nevertheless, given our growing understanding of these dangers, it is our duty to educate pet owners about the risks both to their pets as well as to themselves and their families. In terms of the implications to hospitalized patients in the ICU, animals fed raw-meat based diets pose a tangible risk to other ICU patients. Hospitals should adopt policies and protocols to reduce the risk of disease transmission within the hospital environment related to animals fed raw-meat based diets. We should remain vigilant to the risks posed by the growing trend of feeding raw-meat based diets to dogs and cats, and frequently re-evaluate our policies and procedures so that we can minimize the risk to our patients.

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