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Nutrition Nuggets is the newest offshoot of petMD's Cat Nutrition Center. Each week Dr. Coates will use her expertise and wisdom to blog about the intricacies of cat nutrition.

Diets for Food Allergic Cats: Hydrolyzed versus Limited Antigen

January 18, 2013 / (4) comments

In response to my statement, "I’ve had much better luck diagnosing and managing food allergies in dogs since I’ve started relying more on hydrolyzed foods…" that appeared over on the canine version of Nutrition Nuggets a couple of weeks ago, TheOldBroad asked the following questions:

Have you ever dealt with a cat with food allergies?

Do you think this protocol would be advantageous for felines?

The answer to the first question is, "yes." I’ve treated a number of food allergic cats during my career. The second question is trickier….

First a review. Proteins are what incite the immune system in a true food allergy, so it shouldn’t be too surprising that protein-rich foods are the primary culprits. A review of 56 cases of feline food allergies showed that beef (29%), dairy (29%), and fish (23%) were responsible for over 80% of the incidences. Carbohydrates contain some protein, but they play a lesser role. In this study, wheat was an allergen 5% and corn 7% of the time. Other recognized allergens were chicken (7%), lamb (7%), and egg (4%). Therefore, one way that pet food manufacturers have designed diets to deal with food allergies is to avoid including common allergens. Instead, they rely on unusual ingredients like duck and potato.

Another way of going about making a hypoallergenic food is to break the proteins down into such tiny pieces that the cat’s immune system no longer recognizes them as proteins and potential allergens. This is how hydrolyzed diets work.

Now on to the hydrolyzed versus limited antigen diet debate in cats. I’ve never used a hydrolyzed diet to diagnose or treat a cat that I thought suffered from a food allergy. These are fairly new products so maybe the opportunity has simply not presented itself, but in my experience, food trials in cats using limited antigen diets have always seemed to go a bit more smoothly than they do in dogs. This might be true for a number of reasons. Perhaps cats come in contact with fewer potential allergens in their diets so it’s easier to eliminate them from a limited antigen diet. Or, maybe it’s due to some inherent difference in the disease process between the two species. Whatever the reason, I’ve never had reason to suspect that a cat’s lack of response to a food trial has been caused by an inability to find ingredients to which the individual doesn’t react.

So I think I’m going to maintain the status quo with regards to diagnosing and treating food allergies in cats. I’ll rely on limited antigen diets as my food of choice, but if I ever run into a case that I think could benefit from a hydrolyzed diet, I’ll sure be happy they are there as a Plan B.

As an aside, when I was researching this article I noticed that four out of ten "limited ingredient" cat foods advertised on a major food retailer’s website mentioned that they included some type of fish on the front of their labels. That doesn’t appear to make a lot of sense based on the results of the study I cited above.

Dr. Jennifer Coates

Image: mk30 / via Flickr

Comments  4

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  • Cats with Allergies
    01/18/2013 10:29pm

    My Ivy Elizabeth (RIP) was highly allergic to so many things, She had food allergies as well as kapoc, dust,wool, etc etc etc. She itched so badly that she licked off her fur from the "waist" down. Poor half-bald, itchy kitty!

    One of the things we tried as switching her to a home-cooked lamb diet. Ivy was completely unimpressed and refused to eat it until I picked out the rice. Just eating meat caused her to be constipated, so that food trial went out the window.

    We tried skin testing which proved to be very unhelpful. Eventually, we attempted a RAST test, knowing we had only a 50-50 chance of getting decent results.

    Ivy got allergy injections based on the RAST test which took care of all her problems. Oddly, after about 10 years, we were able to stop the injections and she never had another problem with allergies.

    I sure wish we had been able to try hydrolyzed foods.

  • 01/19/2013 06:41pm

    Hi TheOldBroad. Your allergy testing wouldn't have worked because allergy testing is done on raw proteins, not cooked, and there is a difference.

    As whole rice, (rice bran), is one of the two best fermentable fibers for both dogs and cats, it is too bad you didn't try grinding whole rice before including it in the food you home cooked, as that might have worked well, preventing constipation.

  • 01/20/2013 12:17am

    Thanks, Westcoastsyrinx.

    Sure wish I had known that 20 years ago. Iny Elizabeth might have gotten some relief much sooner.

    Bless her heart. This was before i really knew anything about caring for a critter with problems (and really not many resources to consult). She patiently suffered through lots of trial and error until we finally got her some real help.

    I'll definitely tuck the information away for future use.

  • Carbs and protein
    01/19/2013 06:53pm

    Dr Coates, you might want to check out the validity of the following statement? "Carbohydrates contain some protein, but they play a lesser role. " NOT possible. I think you may have meant to imply that carbohydrate SOURCES in pet foods such as potato contain very minor amounts of protein too. This is true of all carbohydrate sources and why you have to use "novel" carbohydrates as well as proteins as the protein in the carbohydrate source may be at fault for the intolerance/allergy.

    As for the fish content, our pets need omega fatty acids found in fish oils, so that may be the reason for the reference. Fatty acids/oils are the primary nutrient used to battle intolerance/allergic reactions.

    We found it very difficult to find dog food that didn't have some form of chicken, either protein or fat, with one dog. Even when it wasn't on the labelling we think that possibly the same equipment had been used for processing as had been used for something with chicken in it, as the poor dog went through months of trial and error before we found a food that didn't some essense of his chicken allergy.