Vet Blog

09/26/09

Which Ingredients are Most Likely to Cause Food Allergies in Dogs and Cats?
Dr. Eric Barchas, DVM

Hereford_bull_largePet food discussions seem uniquely capable of getting readers of this blog excited. Let’s shake things up.

Recently a reader brought up a question in the discussion of corn as a pet food ingredient. The reader was curious about the allergenic effects of corn. Is corn likely to cause allergic reactions in dogs and cats?

Cats and dogs with food allergies most commonly suffer from skin and ear problems. Gastrointestinal upset also is possible.

Numerous studies have been performed to assess the most highly allergenic food ingredients. A paper published in the September, 2002 issue of Advances in Small Animal Medicine and Surgery attempted to tabulate the results of 22 different studies into a cohesive set of data. This “study of studies” has the advantage of large sample sizes that are likely to be statistically significant. It has the disadvantage of being authored by Philip Roudebush of the Hill’s Science and Technology Center. Although I can’t see any evidence of data twisting in the paper, readers should be aware that the data were tabulated by a person employed by a pet food manufacturer. Consume as many grains of salt as you desire while reading the results.

The leading food allergens in dogs as determined by the study of studies are listed below. Numbers in parentheses indicate percent of food allergy cases caused by each ingredient. They do not indicate the likelihood that a pet will suffer an allergic reaction after consuming the ingredient.

  • Beef (34%)
  • Dairy (20%)
  • Chicken (20%)
  • Wheat (16%)
  • Egg (7%)
  • Lamb (5%)
  • Soy (5%)
  • Corn (3%)
  • Pork (2%)
  • Rice (2%)
  • Fish (1%)
  • In cats, the following allergens were found to be most problematic.

  • Beef (29%)
  • Dairy (29%)
  • Fish (23%)
  • Lamb (7%)
  • Chicken (7%)
  • Wheat (5%)
  • Corn (5%)
  • Egg (4%)
  • A different study of studies was published in April, 2006 in the online journal Critical Reviews in food Science and Nutrition. The authors were Belgian, and in a quick review of the matter I could not find evidence of links to pet food companies. Here are their conclusions.

    The leading allergens in dogs as determined by the authors are beef (36%), dairy (28%), wheat (15%), egg (10%), “diverse” (includes corn, rice, “biscuit”, chocolate [They're feeding chocolate to dogs in Belgium?! Don't they know it's potentially toxic? And isn't Belgian chocolate too good to give to dogs?], and gluten) (10%), chicken (9.6%), “canned foods” (8.6%), soy (6%), “dry foods” (6%), pork (4%), rabbit (1%) and fish (1%).

    The authors concluded that the leading allergens in cats are “commercial foods” (ingredient causing allergies undetermined) (25%), beef (20%), dairy (15%), fish (13%) “diverse” (includes penicillin, “brand’s essence”, gluten, and viscera) (11%), lamb (7%), poultry (5%), barley and wheat (5%), additives (2%), rabbit (1%) and egg (1%).

    Percentages in both studies may not add to 100 due to rounding.

    Readers are invited to post links to additional studies in the comments section.

    Photo: may cause allergic reactions in dogs. That leaves more for me!

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    09/19/09

    Is Corn Just a Filler in Pet Foods?
    Dr. Eric Barchas, DVM

    cornThe number two question I have noted in response to my plea for questions from the head of Iams relates to corn. Why is corn in pet foods? Is it just a filler?

    To answer this question I will rely in part on my own original research. I tested the corn-as-a-filler hypothesis personally.

    When I was a freshman in college, dinner was served family style each night in the dormitory’s cafeteria. At that time I had not yet ascertained that I was destined to be a clinician rather than a researcher. Therefore I decided to undertake an experiment.

    One night my table was served a portion of canned corn. A large volume was left over at the end of the meal. In the name of science I consumed the leftover canned corn. It amounted to at least two cups. In order to ensure the validity of my experiment, I took care not to chew the corn.

    The next morning a scientific breakthrough occurred. I discovered, decisively, that unchewed corn is not digestible.

    The key word, however, is unchewed. The outer husk of a corn kernel is not digestible by cats, dogs, or humans. Ground up corn is a different story.

    I remember learning in nutrition class in vet school (and to answer, in advance, the skeptics who will bring up links between pet food companies and veterinary nutrition departments, I have this to say: give me some credit. You don’t think I’d see through that?) that corn is actually a good source of protein for pets.

    When I was in Ohio (remember folks, it was Ohio. Not Hawaii, and certainly not Rio) on Iams’ dime, various Iams representatives pointed out that the price of corn has skyrocketed in the last year as demand for corn-based ethanol and other biofuels has taken off. They state that if corn were just a filler they would be wise to seek out a more economical filler.

    I also asked about the future of grain-free diets. Dan Rajczak (head of Iams and and Eukanuba) states that the company is investigating these diets at their Louisville, Ohio research center. If their research shows these diets to be more optimal for pet health (and perhaps more profitable?), Iams may begin to move away from grains.

    But enough about corn and grains. I also found out where the names Iams and Eukanuba come from. Iams is the last name of the company’s founder. Eukanuba apparently is something that young men in Dayton, Ohio would say when they saw an attractive woman about a century ago. In other words, Eukanuba means hot chick.

    And that wraps up the Iams thread. Tomorrow the Vet Blog will be back to feline Q and A. Dog lovers, fear not. I’ll start adding in some dog topics again soon.

    Photo: A scientific experiment waiting to happen! By Vassia Atanassova.

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