I have covered the raw diet issues since the very start of this blog, which is about nine years now. My articles on the subject are collected here. Very little has changed in my assessment of the evidence over this time. The bottom line is clear:
There is evidence of risk in feeding raw, including infectious disease, parasites, and injury from raw bones. There is no scientific evidence, only anecdote and dubious theories, to demonstrate any benefits from feeding raw.
A new study has recently been published which adds to the already considerable evidence of risk from infectious disease.
Martinez-Anton, L., Marenda, M., Firestone, S.M., Bushell, R.N., Child, G., Hamilton, A.I., Long, S.N. and Le Chevoir, M.A.R. (2018), Investigation of the Role of Campylobacter Infection in Suspected Acute Polyradiculoneuritis in Dogs. J Vet Intern Med, 32: 352–360.
This was a case control study conducted in Australia and designed to look for associations between the occurrence of a serious neurologic disease, Acute Polyradiculoneuritis (APN) and infection with the bacterium Campylobacter sp. This bacterium has been identified as a common trigger for the analogous disease in humans, Guillain-Barré Syndrome. Because exposure to raw chicken is a common source of Campylobacter infection in humans, the feeding of raw chicken, and other raw meats, was one of the variables evaluated in this study.
The results were quite clear. Dogs with APN were far more likely to be have Campylobacter than healthy dogs, and dogs with APN were also much more likely to have been fed raw chicken and other raw foods.
This type of study only shows an association, not a definitive cause-effect relationship. A prospective randomized controlled trial would be needed to prove feeding raw chicken can cause Campylobacter infection which can then cause APN. However, such studies are not always necessary or appropriate to guide us in reducing our risk of disease. Case-control studies are the main source of evidence showing smoking increases the risk of lung cancer, and certainly a randomized trial in which some people are made to smoke for years and others are not to definitively prove this relationship would be unnecessary and unethical.
We are more often willing to inflict harm on animals in order to investigate the causes of disease, so it is possible someone will do such a study in dogs even though we would not do it in humans. However, it is clear that this study, in the context of the existing evidence in veterinary and human medicine, supports the clear health risks eating raw meat.
Proponents of raw diets will certainly argue that the risk is small compared to the benefits. Unfortunately, no scientific evidence yet exists to show any benefits, and personal anecdotes or theories about the natural history of dogs are not sufficient reason to ignore the robust scientific evidence of the harm that raw diets can cause. Unless some reliable research evidence emerges to show meaningful health benefits from raw feeding, there is no good reason for pet owners to participate in this dangerous fad.