By Dr Suff Suharju (GRV Senior Veterinarian)
Raw meat-based diets (RMBD) are prevalent in the greyhound industry with most greyhound trainers generally preferring a RMBD combined with a commercially prepared dry food (or bread). It is not popular practice to exclusively feed high quality commercially prepared dry foods which are nutritionally balanced and complete, and therefore do not require supplementation according to what is understood of the canine diet. This is not too dissimilar to the pet owning community where the social aspects of feeding by-products of the human food industry are desired. The desire to prepare the food themselves with the ability to tailor the diet as required to influence the health and well-being of the greyhound are common reasons for choosing to feed a RMDB, which is further reinforced if greyhounds perform well.
RMBDs are those diets that include uncooked or undercooked ingredients derived from domesticated or wild-caught food animal species and can include skeletal muscles, internal organs and bones. They can be further divided into commercially-available or home-prepared, however most greyhound trainers feed home prepared RMBDs.
The Current Evidence
There are very few supporting studies for the benefits of RMBDs, however there are many compelling scientific articles on the infectious disease risk to dogs and humans when fed RMBD.
A survey on feeding practices amongst the general companion animal population of Australia found that of those feeding exclusively-RMBDs (16.2%) believe their pets to be healthy1. One paper that proponents of RMBDs rely on discusses the potential loss of a digestive enzyme found in fresh food when processed. RMBD proponents believe that processed food does not provide the potential maximum energy content. However, the same paper concluded that there is no direct evidence that the lack of this digestive enzyme in processed food will lead to any disease process.
There is evidence that RMBDs are nutritionally unbalanced, such as one study that reported on the nutritional analysis of five RMBDs (both commercially available and home-prepared) and found that there were deficiencies in potassium, magnesium and zinc, and high in vitamin D. Greyhound trainers supplement their RMBDs with various products, and this often leads to unnecessary over-supplementation, which can be detrimental to the health and racing performance, and an unnecessary cost to participants.
There are several strong studies that identified the increased presence of infectious agents in RMBDs when compared to commercial dry and wet food. The 15 studies commonly found Escherichia coli and Salmonella enterica, but also found Campylobacter, Cryptosporidium, Neospora and Toxoplasma. There were no significant association between the type of raw meat and the agents isolated.
A recent study conducted by The University of Melbourne identified a significant association between small breed dogs and the rare but debilitating neuropathy (Acute Polyradiculoneuritis or APN) when fed chicken necks. Affected dogs were also more likely to test positive to Campylobacter, which the authors strongly suspect is the immunological trigger that causes the condition. APN has been proposed to be the canine equivalent of the human Guillain-Barre syndrome (GBS), where Campylobacter is considered the triggering agent in 40% of patients. The bacteria can be present in undercooked chicken, unpasteurised milk products and contaminated water. The author suggests there may be a genetic predisposition, or small breed dogs may be at increased risk as they are more likely to be fed chicken necks, but concluded further studies are required. The feeding of raw chicken has been commonplace in racing greyhounds for some time (decades), and the authors are unaware of any confirmed cases of APN involving a greyhound, and none of the 27 cases in this study were a greyhound. We would support detailed veterinary investigation of any suspected cases.
A study conducted on a greyhound breeding facility in the USA found Salmonella enterica isolated in 66% of the population (N = 133). The study concluded that this accounts for the common diarrhoea outbreaks within the greyhound industry.
A few studies have identified an increased risk of Salmonella outbreaks in immunocompromised individuals; i.e. those whose immune system is not functioning optimally due to disease, stress, extreme age (young/old), physical condition or medication history. Dogs that are fed RMBD were 11.4 times more likely to have Salmonella.
In addition to diarrhoea outbreaks, other health risks previously reported include fractured teeth and intestinal injury if bones are fed, blindness, epilepsy, encephalitis and death.
A study investigating gastrointestinal parasites within Australian greyhounds by Murdoch University found 57.7% of 561 greyhounds had evidence on faecal analysis of parasites. Sarcocystis (32.1%), Cystoisospora (6.4%), Neospora/Hammondia-like (2.1%) and Taenia (0.35%) are parasites prevalent in greyhounds from the feeding of RMBDs, and their true prevalence is likely to be higher given this study was based on faecal analysis alone.
It should also be noted that there is risk to human health with many of the above diseases capable of causing infections in humans, therefore appropriate hygiene and management practices are necessary to avoid risks to those working in the industry, particularly those people who are immunocompromised.
As a general rule, commercially prepared dry foods of reputable brands are nutritionally balanced and produce little risks. However, the recent recall of Advance Dermocare due to a cluster of cases of megaoesophagus of unexplained cause has prompted calls for regulation of, and government inquiries into, the pet food sector, with a Senate Inquiry now opened. It appears possible that an unknown toxin has caused the issue, however further investigation is occurring at The University of Melbourne.
In addition to the infectious disease risks above, the feeding of meat that is unfit for human consumption (knackery meat) will significantly increase the risk of returning a positive swab as advised in GRV’s Feeding, Medication & Supplement Guidelines. While cooking meat, or in some cases freezing, will eliminate the risks associated with the infectious diseases above, they are likely to have little effect on the risks associated with returning a positive swab. Therefore, the feeding of human consumption meat, or so-called cleaner meats (e.g. chicken or kangaroo) that are unlikely to have been treated with prohibited substances, are preferred to reduce prohibited substance risks.
The feeding of any RMBD will still have the associated infectious disease risks referred to above, and so cooking will reduce those risks, as will improving food preparation and hygiene practices. However, as feeding practices are influenced by tradition and folklore and are ingrained within the industry, switching meat sources or how meals are prepared may be a difficult message to spread, particularly if participants believe they have never had a problem with their previous methods.
RMBDs have an inherent risk of bacterial and parasitic contamination, and dogs that consume RMBDs pose a risk of infection to themselves, other dogs and people. Those individuals with a known or suspected low or compromised immunity such as the young, elderly, pregnant, ill-affected and on certain medication, are at greater risk of contracting infection and should takes steps to avoid contact and/or maintain adequate hygiene when handling dogs fed RMBDs.
It is recommended participants give consideration to solely feeding a reputable commercially prepared dry food, however as this is an uncommon practice amongst greyhound trainers, it will be difficult practice to change. Alternatively, the feeding of cooked meat that is fit for human consumption will reduce the risks of infectious disease and prohibited substances, providing high hygiene standards are implemented and maintained in food-preparation and storage areas. GRV does not support the feeding of knackery meat as it commonly leads to positive swabs, while handling practices tend to increase the risk of disease.
Those who continue to feed RMBDs should conduct their own individual risk-benefit analysis. They will need to identify if they are at greater risk, or if they have had previous outbreaks, and ensure they undertake necessary steps to mitigate those risks. Where feeding RMBDs are maintained, ensuring high hygiene standards are implemented and maintained in food-preparation and storage areas is the bare minimum, but it is very likely outbreaks of diarrhoea from a ‘bad batch’ of meat will continue, as will the high prevalence of parasitic infection.
- Morley, P., Strohmeyer, R., Tankson, J., Hyatt, D., Dargatz, D. and Fedorka-Cray, P. (2006). Evaluation of the association between feeding raw meat and Salmonella enterica infections at a Greyhound breeding facility. Journal of the American Veterinary Medical Association, 228(10), pp.1524-1532.
- Freeman, L., Chandler, M., Hamper, B. and Weeth, L. (2013). Current knowledge about the risks and benefits of raw meat–based diets for dogs and cats. Journal of the American Veterinary Medical Association, 243(11), pp.1549-1558.
- Hinney, B. (2018). The trend of raw meat-based diets: risks to people and animals. Veterinary Record, 182(2), pp.47-49.
- Martinez-Anton, L., Marenda, M., Firestone, S., Bushell, R., Child, G., Hamilton, A., Long, S. and Le Chevoir, M. (2018). Investigation of the Role of Campylobacter Infection in Suspected Acute Polyradiculoneuritis in Dogs. Journal of Veterinary Internal Medicine, 32(1), pp.352-360.
- Algya, K., Cross, T., Lee, A., Lye, L., de Godoy, M. and Swanson, K. (2017). Fecal microbiota and metabolites of adult dogs fed extruded, mildly cooked, and raw diets. Journal of Animal Science, 95(4), pp.111-111.
- Lefebvre, S., Reid-Smith, R., Boerlin, P. and Weese, J. (2008). Evaluation of the Risks of Shedding Salmonellae and Other Potential Pathogens by Therapy Dogs Fed Raw Diets in Ontario and Alberta. Zoonoses and Public Health, 55(8-10), pp.470-480.
- Parr, J. and Remillard, R. (2014). Handling Alternative Dietary Requests from Pet Owners. Veterinary Clinics of North America: Small Animal Practice, 44(4), pp.667-688.