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Q. and A. with a Pet Nutritionist

Blog dog eating dog health pet health pet nutrition


Dr. Joe — Joseph J. Wakshlag — a clinical nutritionist at the Baker Institute for Animal Health at Cornell University, is answering readers’ questions about pet food. He is no longer taking questions.

I was not expecting over 100 questions, since other forums I have dealt with have only generated a handful of questions, I guess this tells the story of The New York Times readership. Since the response seems to be overwhelming, I am only picking questions as they relate to overall “concepts in nutrition.” And yes there is a Dr. Joe, but he does have a day job which pays the bill’s, so I am afraid that I will not get to a majority of the “my dog” and “my cat” questions. I am also refraining from answering the “personal pet” questions because I cannot do your individual animal justice in a blog in which a two-page questionnaire is essential to understanding the medical needs and goals for each of your animals. For those looking for balanced homemade diets for healthy dogs and cats, there is a veterinary-run service I recommend called It’s relatively cheap and will likely be something useful for those of you looking to home-cook. Cornell University Hospital for Animals also offers similar services.

I would just like to know a good home-made dog food recipe for my 10 year-old pitbull -shar pei mix, or even the correct percentage of protein, vegetable, carbohydrate, fat, etc. as well as any supplements to add. Even my vet wasn’t 100 percent sure of the percentages. – T. Goodridge, Maine

I wish I could provide this basic information, but without any idea of the known medical history, predisposition, body weight, body condition, this is very difficult.

I would like to touch on the idea that your vet does not have advice for you on this subject. I think we expect our veterinarian to know a little too much in today’s day and age. Vets are expected to be infectious disease experts, pediatricians, surgeons, endocrinologists and yes even nutritionist. We don’t expect this of our general practitioners, but for some reason expect this of our vets. It’s a tall order particularly when we work in the multiple species component. This is the reason the veterinary medicine also has specialists.

I breed and show dogs. I’ve had dogs since 1987. I feed my dogs a conventional commercial diet and I have never had a dog with any kind of food allergy. I usually have 5-6 dogs at any one time. My dogs have been living long, healthy lives into their teen years. Have I just been very lucky? I hear people talking about their dogs having allergies and problems with food all the time. I can’t believe that I’m the only person with dogs that do well on an ordinary commercial dog food. I do read about dog foods a lot and make sure that I’m using a good food, but it baffles me that so many people/dogs have trouble with foods. I used to add supplements and vitamins to my dogs’ diet but now I just feed the dog food. They have beautiful coats, great skin, healthy dogs. I guess I don’t understand why other owners and dogs have so many problems and I’ve been so lucky. It seems like, in all these years, with so many dogs, I would have had a problem if there was something wrong with commercial dog food. – Eshever, Tennessee

I do agree with you as I have been using commercial foods all of my life, and yes, I too have dabbled with feeding meat to my performance dogs. However, I have decided against it for a number of reasons. I think in today’s market there are so many choices that it’s actually hard to justify feeding homemade diets in a kennel like yours. Not only is the expense greater than what the article suggested in general, if using high quality produce and meat. Also there are risks of sub-clinical to clinical deficiency if not done correctly. This is why we as nutritionists harp on these things since we are the ones that end up seeing the problems due to diet. Can it be done correctly, absolutely! But I think one has to do the research and become comfortable knowing that they are meeting recommended daily requirements. Even though most of us as humans rarely meet our recommended daily requirements!

Tomorrow, for the second time in seven years, we take a cat for radioactive iodine treatment for hyperthyroidism (not the same cat). The condition seems to be increasingly common. Is that true? What evidence is there that hyperthyroidism is associated with or caused by the canned and dry food that these guys eat their entire lives? How solid is that evidence? Michael, Vancouver, B.C.

This is a hard question to address since we do see it more often, but we also see A LOT more older cats in vet offices than we did 10 to 15 years ago. There have been some implications that food may be correlated to incidence of the disease, and though I am no expert in hyperthyroidism the most interesting correlation has been to canned foods. A fairly extensive study from Michigan State suggested that the chemicals using in the lining of some of the pop-top cans might be problematic. It’s probably way to early to say, but it is definitely one of the top five medical problems in older cats today that needs to be addressed with more research.

I’d be interested to hear your opinion on the different “tiers” of pet foods these days. It seems like there is mass-market, high-end mass market (i.e., Eukanuba), even-higher-end dry food (often high-protein, like Blue Buffalo or EVO — which we use), dehydrated natural foods (e.g., Honest Kitchen), and finally cooking real food for your dog. What do you think is worthwhile and actually has benefits for our favorite pup? – CT Dub, San Diego, Calif.

Well I must say I am a bit superstitious about food and feel that what comes out in the end is a pretty good indicator of the performance of a food. I deal with sled dogs and some are high octane dogs and just do better on certain foods. I think I can say there are some benefits from certain things in food. I am a fan of seeing a soluble fiber source, as well as a source of long-chain omega-three fatty acids. Often the higher-cost foods have had a “more cerebral” thought process put into their formulation, whether your dog needs some of these nutrients is debatable, particularly the “kitchen sink” foods, as I like to call them. These foods add every know vegetable, fiber source, probiotic and herb into the mix to catch your attention.

What I don’t understand is why certain ingredients that are in our diets such as corn, soy and rice have been getting a bad rap. Corn and rice are highly digestible have low fiber content compared to other grains and too my knowledge are associated with allergies only due to the sheer number of products that have these things in them. These carbohydrate sources are essential to the processing and extrusion of kibble. If it’s grain free it doesn’t mean carbohydrate free.

One of the worst things we can do is speculate based on human conditions. Dogs and cats don’t get the same kind of heart disease or cancers that humans get, which is the major centerpiece for nutritional advice and things that tend to cross over into pet foods. One reader asked if there was a dog and cat food pyramid like in human nutrition. Unfortunatley not, but rest assured the pyramid would look dramatically different than the human one!

Also, as something of an aside, we bought some frozen raw bones for our dog from our local “organic/natural” pet food store. They gave him diarrhea, likely from bacterial contamination. The first time he started having voluminous diarrhea that lasted for 7 days despite bland diet, etc., until we treated him with Flagyl (and then it rapidly cleared), but we weren’t sure that time of the cause. The second time we gave him a bone he also immediately started having diarrhea, and once we started Flagyl 2 days later it again cleared up immediately. I’m a (human) physician and was pretty convinced it was the bones that were at fault. A lesson to me about the risks of a more “natural” approach.

Thanks for your insight.

“Natural surely” does not mean not cooked. When advocates of raw diets talk about “enzymes” and native forms of proteins, they are also talking about enzymes that are in tissue that actually inhibit protein breakdown. So for every natural enzyme that might potentially help with digestion, there is likely one to inhibit food breakdown. And once it all reaches a pH of 2 in the stomach and pepsin in the stomach, these enzymes don’t have a fighting chance. Actually cooking in many instances is essential to actually get to certain nutrients in the food. Therefore, I am a fan of cooking foods due to digestion issues and of course zoonotic threats to people in the environment. In your dog’s case it sounds like either a bacterial problem, but more likely a food tolerance issue.

Another reader asked about the cooked vs. raw debate and whether there was any proof of zoonotic transmission. Its assumed that 1 percent of bacterial zoonosis is through animal contact so I would say there is some evidence. Additionally literature based from Dr. Scott Weese in Canada suggests that shedding of salmonella or enterogenic e-coli species are between 7-15 times greater if a dog is fed raw. Furthermore he did a study looking at what methods of disinfection are best in the kitchen after contaminating a dog bowl and the results are shocking. Nothing was 100 percent and most things we do to decontaminate are pretty ineffective. Is there risk? Epidemiologically, yes.

I was under the impression that providing domesticated cats a vegan diet was particularly harmful to their health. For example, don’t cats tend to go blind without necessary amino acids in their diets — amino acids (taurine) found exclusively in meat? – Emily, Cambridge, Mass.

I have a family member who has put all of his pets, dogs and cats on a vegan diet, for ethical reasons. Is it possible for dogs and cats to do well on such diets? The pets do not live that long, especially the cats…which typically only live for 4 or 5 years. Needless to say, I am very upset about all of this, and would like an expert opinion. – Catherine, Wilmette, Ill.

I fully agree that cats do better on a carnivore diet due to their intricate metabolism that actually makes them carnivores. Essential nutrients include taurine, arachidonic acid, arginine and higher amounts of other amino acids and vitamins are the major differences. However, vegetarian diets can be made for both cats and dogs. I would say that if you are attempting to try these things due to ethical reasons, then try to find a commercial food that is well fortified with many of these nutrients I discussed. I too have seen disastrous results of ill thift in cats being fed a vegetarian diet and do not recommend trying to make a vegetarian diet for a dog without guidance from a nutritionist (preferable a board certified Veterinary Nutritionist that is part of the American College of Veterinary Nutrition). I don’t recommend even trying the home-made vegetarian approach for a cat.

hi dr. joe; “neptune” and i would love your thoughts on dry vs canned food for cats. is there any sort of dry food that wont promote obesity? do the health benefits of canned cat food outweigh the convenience and tastiness of dry food? neptune is delighted that this is in diner’s journal–wnere else but new york?? – babs in gramercy, new york, ny

From my perspective I would have to say that it really depends on the medical condition you are most worried about. For years there were many advocates of dry food for dental health, but unless the kibble is made correctly it’s a long shot to say that kibble will really help with dental problems and since one of my cats swallows the kibble whole it’s not helping him one bit! More recently from an evolutionary and urinary tract health stance canned food in general has higher protein and fat therefore recapitulating the carnivore better than the average dry food. To boot, canned food provides more water for a cat eating a normal amount than most cats actually take in from the water bowl. So in the end I think there are advocates of both depending on what you are most concerned about in your feline friend. I personally like to start kittens out eating both canned and dry since cats are harder to introduce new forms of food to than dogs. If you feed only dry food and then at 5 years old your cat develops urinary tract issues or kidney issues canned food is a better choice for the water content and that cat may refuse to eat this new form of food. On a side note the idea that dry food causes diabetes or obesity has yet to be proven. As for obesity, it’s still the mantra of calories in and calories out; if diagnosed with diabetes, a cat should be fed a lower carbohydrate higher protein diet to help control the blood glucose.

On the side of dental health, for both dogs and cats, there are products out there on the market that have a veterinary oral health council seal of approval. It means that the manufacturer of the product submitted their proof of concept that it helps reduce tarter or calculi, and has been approved by veterinary dentists. These products have been deemed safe and are likely effective without the risk of causing diarrhea, constipation, or lodging somewhere in the GI tract.

Dr. Joe, Could you please comment about the relative proportions of advertising hype vs. science behind the organic/natural superpremium pet foods compared to premium commercial foods such as Science Diet, Royal Canin, Purina and Iams/Eukanuba. As a practicing veterinarian, my understanding is that only the 4 brands listed above actually conduct feeding trials to confirm that the diets keep pets healthy; other commercial diets are approved by laboratory analysis only. Please comment as to whether labels such as “organic” or “human grade” contain any legal or nutritional designation relative to pet foods. My understanding of “organic” is that it is somewhat vague in definition, even in human foods. As to “human grade” foods, all I will say is I don’t eat certain things like bologna.

This is an interesting question and I think I would have to agree with you that only the 4 above have participated in significant research in the field of nutrition with Waltham included. These companies have conducted research internally and externally and have advanced the field for sure. The idea of a feeding trial probably needs to be elaborated on as it’s not a concept people are probably familiar with.

When one buys a bag of food it will have a nutritional guarantee on it. This guarantee will say that it has undergone “feeding trials” or has been “formulated” to meet AAFCO’s requirements. Feeding trials in general are groups of 10 adult dogs (for a maintenance claim) being fed for 6 months and “doing well” on the food base on some blood work and maintaining body weight and “staying healthy”. This has been considered the gold standard and puts the proof in the pudding that the food can sustain the dog without any gross deficiencies. These are expensive trials to run for a product, therefore many of the smaller brands cannot afford to do these trials and formulate based on calculation which is also acceptable, but probably not quite as good as making sure their product can sustain a dog for a period of time.

As far as organic is concerned AAFCO has passed some legislation as to what percentage of the food has to be made from organic to have the organic seal or statement put on the label. I believe if the food has less than 70% organic then they are not allowed to label as such. The human grade story is as vague as you have stated above. We see that and in general I have been told that most meat put into commercial feeds is considered human grade and I would have to defer to someone in the industry to elaborate further on grading of meats. / Free Website Directory / Submit Link
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