Wednesday, 23 September 2009

Dem bones! - The pseudoscience of “raw feeding”

The subject which has been exercising my ‘little grey cells’ of late is the raw feeding of pets. Now you might think (as I did a few months ago before getting embroiled in an especially acrimonious debate with raw food proponents) that feeding dogs and cats ought to be fairly straight forward - go to shop, buy bag/tin of food, feed to pet - job done, easy.

Like most vets and animal lovers I was aware that some people preferred to feed their pets non-commercially produced diets. I had heard of groups such as “Bones And Raw Food” (BARF for short) and “Raw Meaty Bones” (RMB) to name but two and I thought, basically live and let live really, so long as the animal appears happy. I had some concerns about bones doing damage to the gut, or food poisoning from raw meat possibly but I had no idea of the actual level of risk.

For some people however that’s simply not good enough. The raw food brigade, I now know, despise the convenience and peace of mind obtained from feeding a ready prepared diet and feel that we must suffer for the cause by wrestling with great slabs of tripe, disembowelling wildlife and dismembering chicken carcasses to present to our animal companions.

Furthermore, and this is where it gets silly, they are also convinced, like the true believers they are, that any one who doesn’t share their devotion to all things raw is a heretic who deserves to be castigated roundly for their sins. Well, I am exaggerating slightly but the evangelical tone of such groups is quite disturbing at times and they are most intolerant of opposing views.

Their actual arguments vary but the one thing they seem to have in common is a lack of good quality evidence. Raw proponents seem to feel that if they deliver anecdotal evidence loudly, frequently and aggressively enough then that should be enough. This disregard for evidence and condemnation of anyone who doesn’t accept their dogma is what, in my opinion, puts much of raw feeding firmly into the realm of veterinary pseudoscience.

Some anecdotes are more equal than others:

The case for feeding raw is heavily dependant on anecdotal evidence, "my dog’s coat is glossier/teeth are shinier/flatulence has gone since starting to feed raw..." , that sort of thing. On the other hand though when vets and pet owners submit that they also know long lived animals with good teeth, good coats and excellent bowel function which are fed on a commercial diet these claims are dismissed as fanciful or simply wrong. Even if they are true we are told, the animal in question is bound to be harbouring hidden problems which will only come to light years down the line.

Some of the claims for raw feeding, particularly the dental benefits are not unreasonable and it is clear from anecdotal evidence presented that many owners who feed raw are happy with such a diet - fair enough. The whole debate takes a far less convincing turn however with the multitude of additional claims which are considerably more far fetched. Commercial diets are bad, it is claimed because they contain grains which, when fed to dogs, cause stunting of the intestinal villi leading to celiac disease and this phenomenon is actually the cause of death in many elderly, debilitated wild canids as well as commercially fed pets. Yet despite the fact that postmortem evidence for this very specific claim should be easy and cheap for any raw feeding veterinary surgeon to obtain no proof has ever been forthcoming.

Then there’s “argument by revulsion” - advocates of raw feeding reel in horror at the mention of ingredients such as "rice, animal fats, maize gluten, maize flour, wheat gluten, vegetable fibres, minerals, poultry proteins, hydrolysed animal proteins" (technical sounding terms for meat, vegetables and grain), yet would have everyone else feeding their pets deceased wildlife scraped from the tarmac of our highways and byways following road traffic accidents. This appeal to emotion cuts both ways.

Raw feeding is claimed to repel parasites both internal and external, reduce obesity, improve bowel function, improve animal behaviour (to the extent that it has been suggested that feeding kibble could put children at risk of attack by pet dogs), reduce the incidence of hormone problems and arthritis and even improve owners' own immune systems by making them more happy about feeding their pets. There is very little in the way of health problems infact that raw diets will not help with if its proponents are to be believed. The only problem is that not one of these claims is backed by anything other than speculation and anecdote.

What is wrong with anecdotes you might ask - if someone feeding raw food to their dog tells us its coat is in better condition then so be it, raw diets must be good for dogs’ coats. Unfortunately though, it’s not as simple as that. I have no reason to doubt stories of this nature that abound in raw feeding literature but we need to consider other things too. There are very many people feeding their pets on commercial diets who also feel that their pets’ health, coat condition and so forth is also extremely good. In the course of my daily work I hear from many owners how they have changed from commercial brand A to commercial brand B and who also report the exact same improvements as raw feeders claim - but to raw feeders somehow these accounts are less believable than theirs. Like true evangelists they just know that their way is the right way.

To achieve a balanced view, we need to consider not just the alleged benefits of a raw diet but also any potential risks. There are several published papers (LeJeune, 2001; Morley, 2006; Strohmeyer, 2006) which clearly demonstrate the fact that raw food can be a source of various food poisoning organisms such as salmonella, yersinia and campylobacter. Thus householders feeding raw would certainly be likely to be exposed to infection, not just from the raw meat itself but from contaminated furnishings and bedding and contact with the mouth and lips of raw fed dogs. To be fair, what with media scares and super-bug panics we are all probably over concerned with the risks of exposure to bacteria generally, in most cases our immune systems are more than capable of handling such challenges. In other cases however we cannot cope, often with serious consequences. Many cases of food poisoning are reported every year with problems varying from a simple gastroenteritis to, in rare cases, death. Rare yes, we should not be paranoid about this, but it cannot be denied that there are potential risks; this is not, as one raw feeding proponent claimed dismissively, “sensationalist nonsense”.

There are also risks to the pets being fed raw. A recent survey of owners committed to feeding raw (which might reasonably be expected to have a pro-raw bias) was found, with refreshing honesty, to concede potential problems in pets such as food poisoning and obstruction of the bowel attributable to feeding raw (Raw Fit Pet Survey, 2009). Such problems were observed in 11% of cases, a rate vastly higher than any similar complications from feeding commercial diets. Needless to say this section of the survey is discounted by raw feeding proponents who nevertheless are quite happy to accept other sections of the results which suggest positive results.

The Nature Cure:

Proponents of raw food will trot out the mantra, so beloved by all devotees of all things alternative, “nature is best” (usually in capital letters of course, just so we know they’re REALLY SERIOUS!). They maintain that since the dog’s closest wild relative is the wolf then they should be fed the same diet. The observation that the lives of most wolves in the wild are brutal and short, spent mostly fighting, breeding and trekking over hundreds of miles of frozen wastes in search of extremely agile prey seems to have escaped raw food evangelists who see things through somewhat more rose-tinted glasses than most, and believe that a plucked and gutted chicken carcase from the freezer is the same as a freshly killed Caribou. The fact that wolf dentition is pretty much identical to that of dogs is presented as sure evidence that a dog is a pure carnivore. The fact that the slightly less closely related fox also has identical dentition yet exists quite happily on a varied, omnivorous diet is quietly ignored - dentition is not an accurate way to judge whether an animal is a pure carnivore or not.

Much as raw feeders would prefer to believe otherwise dogs are a species in their own right, with their own behaviours and dietary needs, they are not simply “wolf-lite”. Recent genetic studies suggest that dogs have been evolving alongside humans for up to 100,000 years during which time considerable selection pressure has given rise to a unique species which is well adapted to live on a varied omnivorous diet of scraps and pickings from human settlements (Wayne, 1999) and has more friendly, human adapted behaviour (Gacsi, 2005; Gacsi 2009). These selection pressures have been described by one author as “Living in the human niche” (Bleed, 2006).

So, after months of personal abuse from raw diet proponents, who are less than polite (to put it mildly) about anyone who ventures to disagree with their point of view I have concluded that many of their arguments belong firmly in the pseudoscience camp. I am personally still a bit of a "fence sitter" on such matters, there are beyond doubt very many people feeding raw who are delighted with the results, just as there are people feeding commercial diets without problems, I certainly wouldn't condemn an owner for feeding either type of diet. Where the difficulty lies for anyone with a scientific bone in their body though is the extreme rhetoric, excessive claims and verbal abuse employed by raw advocates, all based on flimsy, anecdotal evidence alone. When it is suggested that firmer, scientific evidence is what is required to substantiate the claims that believers feel so strongly about this is dismissed as an attack on the integrity of proponents - the benefits are obvious to raw feeders, they should be obvious to everyone.

The sad thing is that Raw Food Evangelists are their own worst enemies, their abrasive style of debate and their assertions that veterinary surgeons are either too stupid or too corrupt to be able to make an objective decision about feeding pets only serve to alienate people even further. And if their diet is half as wonderful as they claim then the only losers as a result are the animals.

For further reading, have a look at Steve Crane's excellent article "BARF diet mythology" which addresses the subject of raw diets for pets in more depth.


Bleed, P., (2006) Living in the Human Niche, Evolutionary Anthropology 15:8 –10

LeJeune, J.T., and Dale D. Hancock, D.D., (2001) Public health concerns associated with feeding raw meat diets to dogs Journal of the American Veterinary Medical Association, 219, (9), [Accessed 21/9/09]

Morley, P.S., Strohmeyer, R.A., Tankson, J.D., Hyatt, D.R., Dargatz, D.A., Paula J. Fedorka-Cray, P.J., (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, 228:1524–1532 [Accessed 21/9/09]

Raw Fit Pet Survey (2009) [online] [Accessed 21/9/09]

Strohmeyer, RA, Morley, PS, Hyatt, DR, Dargatz, DA, Scorza, AV, Lappin, MR, (2006) Evaluation of bacterial and protozoal contamination of commercially available raw meat diets for dogs, Journal of the American Veterinary Medical Association, 228, (4) 537-542 [Accessed 21/9/09]

Wayne, R.K., and Ostrander, E.A., (1999) Origin, genetic diversity,and genome structure of the domestic dog, Genes and Genomes BioEssays 21:247–257

Gácsi M, Gyori B, Miklósi A, Virányi Z, Kubinyi E, Topál J, Csányi V (2005) Species-specific differences and similarities in the behavior of hand-raised dog and wolf pups in social situations with humans Developmental Psychobiology.47(2):111-22

Gácsi, M., Gyoöri, B., Virányi, Z., Kubinyi, E., Range, F., Belényi, B., Miklósi, A., (2009) Explaining Dog Wolf Differences in Utilizing Human Pointing Gestures: Selection for Synergistic Shifts in the Development of Some Social Skills PLoS ONE 4(8): e6584. doi:10.1371/journal.pone.0006584

Harriett Hall at her eloquent best

A fantastic article by Harriett Hall (aka skepdoc) about scaremongering about swine flu vaccination - I just love her style!

Claim: Mercola says “Injecting organisms into your body to provoke immunity is contrary to nature.”

Fact: Nature kills people. Doing something contrary to nature is what medicine is all about. It’s a good thing.


Mercola’s advice for preventing flu: Eliminate sugar and processed foods from your diet, take a high quality source of animal-based omega 3 fats like Krill Oil, exercise, optimize your vitamin D levels, get plenty of sleep, deal with stress, and wash your hands.

Fact: Washing your hands is a good idea

Mercola claims: “Vitamin D deficiency is the likely cause of seasonal flu viruses.”

Fact: Now really! Vitamin D deficiency in a human body can no more “cause a virus” than it could “cause a cat.” ...


Read it immediately!