New Study on Raw Diets for Dogs Adds Little to Ongoing Debate

I am always on the lookout for research studies concerning raw diets for dogs and cats. A lot of claims are made about the health benefits of raw diets, but there is no substantive body of evidence to justify these claims. In particular, claims that raw diets are healthier than commercial dry or canned pet foods are common, despite no clinical studies making this comparison. I hope eventually such studies will be done, and while I am skeptical raw diets will prove superior, I will be happy to start recommending them if they prove to have benefits that outweigh their risks.

Unfortunately, a recent study of raw diets doesn’t add much information directly relevant to the debate.

Beloshapka, AN. et al. Effects of inulin or yeast cell-wall extract on nutrient digestibility, fecal fermentative end-product concentrations, and blood metabolite concentrations in adult dogs fed raw meat-based diets. American Journal of Veterinary Research 2012;73(12):1016-1023.

The study compared raw beef and chicken-based diets with or without a couple of prebiotics (not probiotics) in research dogs. All dogs were fed each of the diets, and measurements were made of body weight, fecal consistency, nutrient digestibility, and fecal chemicals associated with the presence of prebiotics.  

The short version of the results is:

  • The diets were highly digestible (though previous studies have suggested commercial and cooked fresh diets are also highly digestible, and no clinically significant effects on health have been shown to be associated with any differences in the digestibility of these different forms of pet food.
  • Over the three weeks of time on each diet, all of the dogs remained healthy on all of the diets.
  • The beef-based diet varied more than expected from the predicted nutrient composition, likely due to variation in the nutrient profile of individual ingredients. This is a big problem for homemade diets generally, which are not nutritionally consistent and aren’t monitored for any nutrient excesses or deficiencies on an ongoing basis as commercial diets are.
  • Fecal consistency (but not amount) varied with diet composition, but feces were normal for all dogs on all diets.
  • Fecal volume was lower than previously reported for dry commercial diets, though again the relevance of this for health hasn’t been established. Given the risks of raw diets, feeding them just to have less poop to pick up doesn’t seem sensible.
  • The prebiotics increased the levels of certain compounds in feces, as they have previously been shown to do. This is hypothesized to have health effects, but these have not been demonstrated.
  • Skin and coat quality did not appear to be affected by diet.
  • Interestingly, the mean urine specific gravity on all of these diets was greater than 1.046 for all diets. This is highly concentrated urine for dogs, suggesting potentially inadequate fluid intake. Interestingly, another study from the same institution, one comparing fresh cooked and raw diets with dry kibble in cats, also found unusually concentrated urine, and no difference between raw/fresh and dry diets. This certainly isn’t consistent with the claims that one benefit of raw diets is greater moisture content and less work for the kidneys. 

It is not clear from this report whether or not the diets were formulated to be nutritionally adequate as defined by AAFCO standards, though levels of calcium and phosphorus were reported to be within acceptable limits (though variable based on the specific ingredients in each of the diets). Obviously, nutritional adequacy would be an important issue in evaluating the quality of any diet.

So overall, this study shows that raw diets are highly digestible (which is not surprising, but of questionable importance), that short-term feeding of them under controlled circumstances doesn’t seem to have any negative effects or any benefits unless one considers less poop an important benefit or buys into the still unproven health benefits of prebiotics. There is nothing wrong with studying the variables this project looked at, of course, but it doesn’t have much direct bearing on the controversy over feeding dogs and cats raw diets.

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6 Responses to New Study on Raw Diets for Dogs Adds Little to Ongoing Debate

  1. v.t. says:

    What, no detox symptoms? (the common explanation among raw food advocates to explain vomiting and diarrhea when pets are transitioned to raw food).

    And, no visible improvement in skin and coat? (no more fleas! coat has never been shinier!)

    Only 6 dogs in the study, proof enough for the raw foodists that raw is best!

    I never understood the extreme fixation on dog poo among raw food advocates.

    (sorry, couldn’t resist)

  2. eric rothwarf says:

    I fed my Border Collie Tiger a Raw food diet for 11 years. I made his food myself. He lived to be over 19 and never had any health problems ( except for a cough which started when he was 16. The vet said he had a small throat and perhaps the throat muscles were weakening with his age.) He was healthy and vibrant till almost the very end. He did get fleas and ticks (how could any food change that?) but he never lost his fur or his eyesight. He did lose much of his hearing in the last few years. we went for walks four times per day till a week before I put him down.

    His food was half meat (heart and tongue and 5% liver) and half fruits and veggies ( yams, carrots, beets, apples, green leafy ) and ground flax seed and ground seaweed.

    His poop had a nice fresh smell and he never had smelly farts like some dogs do.

    I know that health has many components and luck is one of them, But I know that his health was helped by this diet.

  3. skeptvet says:

    It’s great that your pet lived such a healthy life. It isn’t, however, proof of anything to do with raw diets. Many people who live to be over 100 years old smoke heavily. Does that mean smoking is why they lived so long? Of course not.

    The only way to know if these diets have halth benefits is to compare the health, lifespan, and other measures for individuals who are nearly identical in every way except for what they are fed. Science is hard work, slow, and imperfect, but it is far more reliable than individual stories.

  4. skeptvet says:

    Already there. 🙂

  5. crinfishle says:

    Not sure I see what you’re getting at. The nutrition is only as spot on as the calculations you do. Cat’s have RDA’s just like humans do and you can pretty easily calculate what you’re giving your cat without even the need for a calculator on a home made diet. Commercial cat food varies wildly by flavor, particularly foods with fish and organ meat. It’s not nearly as easy to keep track of. You have to do a lot of label reading and emailing to follow the guidelines for cats with a commercially fed diet. Things like iodine content get lost in the cracks for a lot of foods unless you’re willing to go the extra mile. Although I’m sure with enough work either method can prove superior depending on where you dedicated your time. kind of hard to label something as inferior in that sense.

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