Science-based Veterinary Nutrition Success Stories

In all the debates here and elsewhere about the relative merits of commercial pet diets and homemade, raw, or other alternatives, advocates of alternative diets often claim that conventional diets are unhealthy. Scientific evidence is not typically provided to support these claims, of course. Similarly, alternative dietary approaches are often claimed to be healthier than conventional diets, but there is no scientific evidence to support this belief. What this means is that, while there may be health risks associated with commercial diets and health benefits associated with alternatives, we don’t know what these are, which animals are affected, or how important the effects may be. Without real evidence, not simply anecdotes, claims about nutrition for our pets are simply opinions.

There is, however, some scientific evidence relevant to these issues. I’ve reviewed some research, for example, looking at claims regarding raw foods. This research so far fails to show any health benefits but does support the potential for risks associated with infectious organisms in raw meat. I have also reported on some of the research showing that homemade diets are often nutritionally imbalanced or incomplete, which would likely negate any potential benefits to the fresh ingredients used to make them.

A recent review paper adds a bit of perspective to this subject by reminding us that there is also research evidence illustrating the beneficial effects of some scientifically formulated diets that veterinarians use for specific health problems.

Davies M. Veterinary clinical nutrition: success stories: an overview. Proc Nutr Soc. 2016 Aug;75(3):392-7. doi: 10.1017/S002966511600029X. Epub 2016 Jun 8.

This brief article discusses the evidence for some of the clearest examples of therapeutic diets that have real benefits for patients. These include:

  1. Diets formulated for dogs and cats with kidney disease, which improve quality and length of life as well as laboratory markers of disease.
  2.  Diets for dissolving certain urinary tract stones, which allow cats and dogs with these stones to avoid surgery
  3. The discovery of the link between taurine deficient diets and cardiomyopathy, a life-threatening heart condition in cats that has been nearly eliminated by dietary supplementation of taurine.

There is also discussion of some less clear examples, including the potential use of dietary therapy for hyperthyroidism in cats and the use of special diets for treatment of arthritis and support of dogs undergoing chemotherapy treatment for lymphoma. These diets appear to have some benefits in these cases, though the evidence is not quite as robust.

Obviously, these examples don’t answer the larger questions about the relative risks and benefits of different dietary approaches. But they do illustrate that using scientific methods, we can develop diets that have measurable and significant health benefits. This is far more promising than simply relying on unsupported nutritional theories, haphazard trial and error, or anecdotes, which is the kind of evidence usually used to justify alternative nutritional practices.

As usual, I expect the comments will include the following invalid arguments, so I will address them pre-emptively:

  1. Vets know nothing about nutrition. Actually, they do know something.
  2. But I fed my dog X and then Y happened. Why We’re Often Wrong Testimonials Lie The Role of Anecdotes in Science-Based Medicine Why We Need Science: “I saw it with my own eyes” Is Not Enough Don’t Believe your Eyes (or Your Brain)

 

 

 

 

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20 Responses to Science-based Veterinary Nutrition Success Stories

  1. Jose RT says:

    Good afternoon,
    I mostly agree with your article when you state that there aren’t clear evidences showing neither advantages no disadvantages between dry petfood and homemade diets.
    But I think you are mixing 2 different things.
    Concerning the ingredients and their safety, the problems with contaminations are not exclusive from raw diets and, for example, there is evidence that micotoxins are commons in commercial dry food (http://www.animalfeedscience.com/article/S0377-8401(15)00055-3/abstract).
    Of course, Salmonella can be present in raw food but, al least in the European Union, the lack of Salmonella in 25 gr. is a requirement for marketing meat, so, using human grade products and a good hygiene at home would provide a low risk of intoxication. Further, we can cook the meat and reduce even more the problems with biological risks. At least, I guess eating raw meat is more safety that going along the street with mouth and nose in close contact with the floor, as most dogs do. I know, this last comment is not very scientific 😉

    On the other hand, we have the ingredients from the ones and the other diets.
    Cereals flours are the main ingredient in extruded dog food and cereal flours are the same as refined carbs, which are, along with sugar, the main responsibles food behind the obesity and diabetes pandemic in humans (Frank Hu, from Harvard Public School University, has written many papers explaining this topic).
    So, Ok, dogs are not human and the direct comparison in technically incorrect…but dogs and humans have a similar microbiome and also suffer from the same chronic nutritional problems and…both extruded dog food and western life-style diet is based on cereal flours. ¿Just a mere correlation? technically, it could be…but I the common sense says me other thing.

    I mean, homemade diets can be perfectly safe and nutritional for dogs.
    Of course, we have to know how to prepare the meals and we have to take basic hygiene rules at home.
    I think it’s a positive thing not to feed, neither a dog nor a human, with a cereal flours based diet.
    I’m not talking about any specific diet…you can use more or less meat, more or less eggs or more of less other than cereals starches (potatoes).
    Of course, cereals can be a part of the diet because they are not going to kill a dog but I think that we have enough evidence and common sense to claim that a fresh food diet is a better option for a dog than a extruded one.
    See you! 😉
    Jose.

  2. skeptvet says:

    Jose,

    Thanks for the comment. There are some areas where we agree, and others where we don’t, so I’ll try to go through the specific comments you make that I would question or disagree with.

    the problems with contaminations are not exclusive from raw diets

    True. However, there is no data to distinguish the relative risk for different types of diets. As a general rule, the risk of infectious disease and parasites is much higher with raw than with cooked meat, which is why we tend to cook our meat and why the CDC specifically warns against feeding raw food to pets. So the risk is undoubtedly higher for raw foods than for cooked homemade or commercial diets, and until t here is evidence that raw diets have health benefits, there is no reason to take such a risk.

    I guess eating raw meat is more safety that going along the street with mouth and nose in close contact with the floor, as most dogs do. I know, this last comment is not very scientific ?

    You’re right, this isn’t a particularly good argument. We touch our hands to things covered in microorganisms and then put these in our nose and mouth all day long. Mostly, we get away with it, but sometimes we get sick. And we know that washing our hands reduces the risk, so we try to do this. Dogs surely do have some exposure to pathogens through lots of behaviors besides eating raw meat, but there is no reason to take the extra risk of eating raw meat as well.

    Cereals flours are the main ingredient in extruded dog food and cereal flours are the same as refined carbs, which are, along with sugar, the main responsibles food behind the obesity and diabetes pandemic in humans

    The idea that cereals in the diet are the main cause of many chronic diseases in humans is a complex and debatable hypothesis. Whole grains, in particular, are a safe and healthy part of a balanced diet, so the issue is more about total calories, fiber content, relative proportions of carbohydrates and protein in the diet, the complexity of the carbohydrates, and many other factors. The idea that “grains=disease” isn’t valid, for humans or any other species. So the idea that commercial diets are bad because they contain grains is not valid. You are oversimplifying here in a way that supports your pre-existing beliefs, but thatdoesn’t legitimately support the overarching claim that homemade diets are healthier than commercial diets.

    homemade diets can be perfectly safe and nutritional for dogs.
    I agree, and I see no problem with feeding a home-cooked diet so long as people a re willing to take the trouble to consult a nutritionist to formulate one properly for their dog’s needs. Unfortunately, a lot of what people are feeding as a “homemade diet” is a haphazard mix of meat and plant ingredients that is nutritionally imbalanced or deficient, and this is likely less healthy than feeding a balanced commercial diet. Homemade diets take more work to get right, and in the absence of evidence that they are healthier than commercial diets (which doesn’t yet exist), it is not reasonable to expect most people to feed them and do so properly.

    I think that we have enough evidence and common sense to claim that a fresh food diet is a better option for a dog than a extruded one.

    And I disagree. This might be true, but the reasons to think so are purely speculative at this point, and it might just as well be untrue. Opinion is not a reliable substitute for data.

  3. Jose RT says:

    Good evening and thanks for your reply!
    Just a few comments to your answer:

    Regarding cooking and contamination, I would say that the main reason why we cook the meat has more to do with culture and taste than with hygiene because we have cooked meat long before we know about the existence of salmonella.
    Cooked meat is more tasty and provide more calories than raw.
    Anyway, I agree that if we cook a steak just before eating it, the food will be virtually sterilized so biological hazards won’t be a problem.
    But It’s not clear, at least, it doesn’t seem to me, than a kibble from a bag is perfectly safe from salmonella and a piece of meat bought at the supermarket won’t.
    Because, we are supposed to cook the meat before eating, but not the kibble before feeding the dog. So, we don’t have data from one or another to compare but we follow differents procedures with one or another, so this is not coherent either…we rely completely in the heat treatment of the kibbles but there are cases of salmonella in dry dog food (http://www.cdc.gov/salmonella/dog-food-05-12/index.html) so, why are we so afraid of raw meat (legally and hygienical marketed) and are so confident regarding kibbles?

    About cereals flours and chronic diseases in humans, I agree this is is a complex and debatable hypothesis but this hypothesis is supported by important observational studies (ok, observational studies only provides hypothesis but they are the beginning of the process).
    It has been shown from some of these studies than refined carbs are not healthy (compared with fats and whole grains) and so we should reduce out intake of, for example, white bread (http://ajcn.nutrition.org/content/91/6/1541.full).
    Whole grains are only safer when they are compared with their refined versions (whole bread against white bread, for example), but low-carb diets and free-grain diets (paleo style) can be even better concerning lipid profiles, for example.
    So, whole grains are not bad, I agree.
    But, the flours that we have in kibbles are not whole grains.
    They are pure starches that are neccesary for the extrusion proccess.
    So well, dogs are not human and there’s a possibility that dogs are more resistant to a high refined carb diet (kibbles) that humans do…but taking into account that dogs are suffering from similar chronic diseases than human beings, I honestly believe that refined carbs are bad for both dogs and humans.
    So, one of the reasons I think homemade diets are healthier is because they are not high in refined carbs (cereal flours). Ok, that’s my belief and my opinion and that is not science…I agree…but according to epidemiological studies in humans, this belief is more or less solid 😉
    It would great being able to run a prospective cohort study comparing whole food diets (low in refined carbs) with kibbles but I honestly don’t think that happen.

    It has been a pleasure!
    Btw, I’m a new member of the EBVMA so see you soon! 😉
    Jose.

  4. skeptvet says:

    Hi Jose,

    Thanks for your response. Always nice to have a reasonable discussion about these things, instead of the fiery rhetoric and abuse I usually get here! 🙂

    I would say that the main reason why we cook the meat has more to do with culture and taste than with hygiene because we have cooked meat long before we know about the existence of salmonella.

    I’m not convinced this is true. Cooking meat is a near universal practice in quite disparate human cultures. It seems more likely to me that it became widespread because the risk of illness following consumption of uncooked meat was high enough that it could be detected by observation, even without controlled studies. You are correct that cooking also increases the caloric value of the meat, which along with reduced disease risk might have conferred a selective advantage on groups of early humans that cooked when in competition with groups that did not. Such “cultural evolution” is impossible to prove, but I think it explains the preference for cooking almost everywhere in the world and through history better than arbitrary social custom and preference would.

    As for the difference between kibble and meat with regard to Salmonella and other pathogens and parasites, of course this only applied to uncooked meat. Since kibble is heat-processed, it will have a lower risk of contamination that raw meat, though not lower than cooked meat. In fact, the risk might be higher in cooked kibble than cooked meat because of the flavorings that are sprayed on kibble after cooking, which are the course of the occasional case of pathogenic bacteria found in kibbles. The risk for kibble is certainly not zero, but it is also almost certainly lower than raw meat. That was the point I was trying to make earlier.

    one of the reasons I think homemade diets are healthier is because they are not high in refined carbs
    Your reasoning makes sense, and I think this is a plausible hypothesis. But of course, many plausible hypotheses turn out to be wrong. I tend to think that, in theory, homemade diets probably are healthier than commercial diets, though I am not sure they would be in practice since I suspect few people would formulate or prepare them correctly. Ultimately, most human nutrition-associated diseases are due to our propensity to select foods for ourselves that are less healthy than the alternatives. We all know we should eat mostly fruits and vegetables with reasonable amounts of whole grains and lean meat or other protein sources. Knowing this hasn’t done much to help us achieve it because we are selected to prefer high-salt, high-fat, high-sugar foods since those were all scarce in the environment in which we evolved (and for most of human history until the last few centuries in the developed world). Knowledge hasn’t done much to help us change our behaviors.

    So I worry that we will not make rational, evidence-based dietary choices for our pets but choices based on what “looks like” a healthy diet to us, which isn’t likely to be optimal for them. I know plenty of clients who think they are doing better for their pets by feeding exclusively raw meat with maybe a few vegetables rather than feeding kibble. This choice, however, is demonstrably less healthy and nutritionally incomplete and unbalanced. So while I agree homemade diets could have some advantages in principle (though this hasn’t bee proven yet), I doubt they will be a healthy alternative to commercial diets for the vast majority of pets. And I think the commercial diets are given entirely too much blame for health problems that are associated with overfeeding or genetic and age-associated diseases. The lifespan of scavenging dogs and cats in developing countries is a lot lower than that of our pampered pets, and I suspect reliable access to the relatively decent nutrition of commercial diets is part of why.

    Thanks for the discussion.

  5. Jo Amsel says:

    Since I have only just discovered this site I would like to comment on Nutrition. As a boarding Kennel owner and also owner of a very large numbers of dogs for more years than I care to admit, I have a very wide experience of different ways of feeding different dogs. I have also trialled dog foods for manufacturers, usually kibble but occasionally new raw foods. I can put my hand on heart and say that there is no hard and fast rule. I have seen old dogs do well with the same cheap,low quality kibbles. No-one can say what is optimum nutrition because each dog is different. We have prevented two GSDs from being euthanised because of uncontrollable colitis – where everything has been done that their vet can do – by simply feeding raw green tripe and raw and cooked homemade type diet. Equally there are dogs that cannot tolerate raw. Some dogs dislike kibble of any variety, some won’t eat chicken. I know one whippet that refused any meat and reared healthy litters on a vegan diet. From the poop point of view, give me a raw/ home cooked, non grain fed dog . Half the poop volume and low odour. For my own dogs I buy a variety of raw ‘completes ‘ which I cook. Although they will eat raw,I cook because I find I need about 25% less to maintain their weight, they also have small quantities of kibble . I feed raw greed tripe once a week because it’s disgusting to cook and I have never met a dog that doesn’t live it,There is a theory about humans, that we developed better because we learned how to cook food and that makes it more bioavailable.There was a programme about it on TV so therefore it must be true! My dogs also eat rabbit poop and it’s free.

  6. No one says:

    Just an itty bitty nitpick (unless I’m wrong on my history):

    “The discovery of the link between taurine deficient diets and cardiomyopathy, a life-threatening heart condition in cats that has been nearly eliminated by dietary supplementation of taurine.”

    – but weren’t those taurine deficiencies the result of people buying dry cat food made with virtually no meat because pet food was a new field with no regulation?

    Which, if that’s the case (though what you said does support the scientific method) supports at least being cautious about the abilities of our knowledge and our processes to formulate food that is truly nutritionally ideal. Especially so because the processing necessary to make dry foods may have effects that are still not completely known, and extrusion itself is so extremely variable (based on moisture, temperature, ingredients, speed of processing etc)

    On that note, I do feel that we’ve made great strides, that pets can and do do fine on extruded foods all their lives, and that processing in and of itself cannot be assumed to make a food “lesser” (like how tomato sauce is more nutritional in certain (?) ways than tomatoes.. unless that was b.s., I don’t remember the source for that)

  7. skeptvet says:

    Historically, commercial diets were taurine deficient, and you are correct that because of incomplete knowledge about the nutritional needs of cats, these diets were inadequate. So yes, scientific knowledge is always incomplete and should never be viewed as perfect. On the other hand, most alternatives to current commercial diets are based on no science at all but simply theoretical reasoning or haphazard personal experience, which is also incomplete and imperfect. Humans, for example, suffered from scurvy and rickets and all sorts of nutritional diseases before scientific understanding of nutrition began to develop. And wild carnivores, despite eating a “natural” diet, often suffer from malnutriton, parasitism, infectious diseases, and even starvation.

    The question is which approach yields the most reliable knowledge over time, scientific research or ad hoc reasoning and experience. I think history strongly supports the claim that science is the better bet, and the fact that is still wrong sometimes doesn’t make the alternatives superior.

  8. Ron says:

    A little off subject but has anyone heard any news on the Law suit brought against
    several of the largest Pet Food Mfg’s, for false advertising? I would tend to agree with the Wysong argument but doubt it will have any effect with the money and lobbying power of these conglomerates.

  9. Mary Anne Whitonis says:

    Hi,

    I have been feeding a homemade diet for years and years. All of my animals live well past their life expectancy for their breeds and are seldom in need of veterinary care. The great thing about homemade diets is that you can also use the broths to make great and healthy soups for the people living in the same house and feed everyone rather inexpensively. Commercial foods are not good for anyone, people or animals. They are overprocessed and when a friend of mine who was in vet school once asked a rep from Hills who lavishes gifts on the vet students to pull them in to sell their products, where they obtained the protein source in their foods my friend never got a straight answer to their question. Don’t feed anyone from a bag, persons or animals. Feed good protein, vegetables and good sources of starch like steel cut oats, brown rice and barley. Dogs who had problems with their skin and digestive tracts suddenly were healed once I switched to a homemade diet. Of course, I went to school for nutrition science and dietetics but anyone can do this for their pets and themselves. It also provides a wonderful bonding experience for the pets and their pet parents because there is no better way to bond with someone you care about than over a good wholesome meal. Vets should be more concerned about providing good nutritional information for the animals than making a profit.

  10. Sabra says:

    When we talk about this, I think we need to agree on some definitions in order to make a better comparison. Maybe for the sake of this discussion, we should assume that the homemade diet is nutritionally balanced. There are many commercial cooked diets that you can buy, which are very expensive, but they do have the AAFCO statement. Also, lots of kibbles do have a lot of simple carbohydrates, but others are low-carb and grain free while others are low-carb and use whole grains. For example, earthborn primitive, taste of the wild high Prairie, Merrick, and wellness core all fit this profile. So maybe a nutritionally balanced home a diet would be better than something like pedigree, but would it also be better than something like wellness core, and with that improvement be enough to justify six times the cost? Many people use stool consistency to defend their food choice. I don’t think that is accurate because whether you eat raw or cooked food and other changes in your diet will affect stool consistency regardless of whether it is healthy. Stella and chewies has also developed a patented process that gets the pathogen’s out of the raw meat, so if that is the case and we are comparing raw feeding without pathogen risk to the cooked homemade and a high-quality kibble option, how does that affect the results? People also claim that homemade food is healthier than canned food. Raw theaters say that cooking is bad because it destroys enzymes that make digestion easier when Raw food actually digests more slowly then cooked food. I read an article about it where they used barium to track the digestion of kibble and raw food in a dogs stomach. Raw theaters also say that dogs were evolved to eat cooked food, but they clearly need a history lesson. Domestic dogs were eating cooked stews with greens in them ever since the middle ages. If you look online, you can find recipes for the stews they made for their dogs that they housed in the Royal kennels at that time. The recipes are basically like stew we would eat today, but blender. Raw feeders say that dogs were so much healthier before kibble came, but even before that, most people did not use raw feeding. They mostly fed their dogs leftovers or they used a special canned horsemeat. Even though we can’t use lifespan as a judge because veterinary care it was different back then, why can’t we somehow get some data on the quality of life for those dogs to at least see if it yields results. Like what did most dogs die of back then and how long did they live and so forth.

  11. Ron says:

    Here is a article that gives some points on the history of pet feed, or food. Your choice.

    [Edited to remove link]

  12. skeptvet says:

    Sorry, Ron, but that is a terrible site full of outright lies and egregious misinformation. You can refer people to it (truthaboutpetfood dot com), but I won’t allow any links to it.

  13. Ron says:

    No worries, I realized it might not fit into your paradigm.

    But just curious what do you consider outright lies, and I can forward it to them, maybe they will correct it, if true.

  14. Tryniti says:

    We do agree about one thing, I’ll add, science IS the better bet. I so wish you and others like you would start using it more. Especially considering that there are NO long term tests done on any commercial pet food – 6 months is the AAFCO “gold standard”. All pets eating commercial food are guinea pigs. Whereas I follow Elizabeth Hodgkins and Lisa Pierson who have been seeing fantastic result by switching to species-approriate diets for years. In fact, statistically speaking raw food is far safer than commercial kibble and canned food, even if it’s HPP or not.

  15. skeptvet says:

    The plural of “anecdote” is not “data.” In other words. the collected experience of people using raw diets is not “statistical” evidence for the safety or health benefits of these diets. If it were, of course, commercial diets would look great, since the collected experience of tens of thousands of pets over decades would suggest they are very healthy. The scientific evidence for such diets is, as you point out, quite limited. However, it is far greater than the evidence for the alternatives.

  16. Ron says:

    I don’t feed raw but thought the below might be of interest.

    I think its likely that there have been far more kibble recalls than raw, granted kibble is far more mass produced.

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3003575/
    The above is from the Canadian Veterinary Medical Association, so it may contain skewed studies to support its agenda.

    Also, here is one that gives the alternate view
    http://www.ukrmb.co.uk/images/Research%20Paper%20-%20Raw%20Diet%20v%20Kibble%20Diet%20.pdf
    It may contain skewed studies to support its bias also.

  17. skeptvet says:

    Ron,

    You need to reduce the volume of material you copy from other sources, for both copyright and practical reasons. If you are going to cite something, limit your quotations to a few senstances, or better yet provide your own brief summary of what it says.

    It is interesting, and consistent with your previous comments, that you suggest the published review of scientific literature might be biased (which it could be, given it is a narrative rather than systematic review), but you don’t suggest the same about the unpublished and far more strident, ideological opinion piece you cite for the pro-raw side.

    In any case, the idea that the evidence for commercial diets is no better than for raw diets is absurd. There are not, it is true, years-long clinical studies of most diets on the market, just as there are no such studies for homemade or commercial raw diets. On the other hand, there is virtually no short-term clinical research or lab animal studies or basic nutritional research to support raw diets, whereas there is a lot of such research to support the use of comercial diets. And while raw proponents like to use anecdotes to support their claims, there have been far more animals fed commercial diets over decades with apparently happy, healthy lives. Raw proponents claim, of course, that diseases of all sorts have increased dramatically since the introduction of such diets, but the simple fact is that they are making this up and there is no evidence it is true.

  18. Ron says:

    I agree, I have posted way to many links and quotes. After looking at all my posts, its a bit embarrassing.
    My apologies.

  19. Patryk says:

    Guess what SkeptVet – Susan Thixton the author of TruthAboutPetFood is offended that you made a libelous statement about her. I’m glad you did considering her ENTIRE site is a collection of libel. everyone knows it should be called Non-Truths about pet food. She can dish it all day but she can’t take it. Props to you for vocalizing your opinion about her conspiracy theories.

  20. Jo Amsel says:

    Let’s not forget that most dogs love variety and given two bowls one with cooked home made and one with kibble, they will invariably go for the home cooked. If we are tempting boarders that are reluctant to eat, it’s not with kibble because it doesn’t work. There is still much to be learned about nutrition human and animal. We feed a wide variety of food ( unless there is a medical contra indication). Our own dogs ( 14 at the moment from 1 – 15 years ) eat every kind of meat ( chicken, turkey, venison, beef , rabbit and game when it’s in season ) some fish, sometimes raw and sometimes home cooked, small amounts of veg and or fruit, egg, good quality commercial wet ,some kibble, some baked, some freeze dried, kefir,yoghourt, kelp, small amounts of rice, oats etc. They eat everything and it’s usually different every day. No digestive issues,great appetites and excellent health. It’s the way we have fed for over 40 years but nowadays there is a greater variety and higher quality that can be bought from small manufacturers which makes it easy.

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