As a Veterinary Nutrition Specialist, one of the more common reasons pet owners would seek out my help was to manage suspected or proven food allergies. In my last post I explained the definition for some ingredients that can be used in commercial dog and cat foods, but when it comes to knowing what is actually in that bag or can you may still be guessing. A recent scientific study on undeclared ingredients in commonly available pet foods pointed out that pet owners may be getting more that they wanted in certain over-the-counter (OTC) foods and treats.
The prevalence (that’s statistics-speak for the number of cases identified each year) for true food allergies in dogs and cats is unknown, but veterinarians and caregivers alike are often quick to blame a food allergy when presented with a dog or cat with itchy skin or diarrhea. Sometimes these cases are a true allergy (i.e., a food protein interacts with an immune cell and causes an exaggerated response), while others are the results of inadequate essential fatty acids (skin problems) or poor digestibility of a food +/- a lack of dietary fiber (diarrhea). The only proven way to diagnose a food allergy is with a dietary elimination and challenge trial. This involves making a list of every food protein (plant and animal) that has ever been fed to the patient; finding a diet (commercially- or home-prepared) that does not include those ingredients; feeding that limited ingredient diet exclusively for 8-10 weeks to see resolution of signs (8-10 week is for skin disease, gastrointestinal signs usually clear up much sooner); and then challenging the patient with either the previously fed diet or individual proteins (plant or animal) and watching for recurrence of sign. One of my own dogs, Raider, had an allergy to beef and was a great example to me of what could happen with re-exposure to an offending protein. I knew that within 12 hours of eating even a single piece of drop hamburger (the reality of life with young kids and dogs) his ears would flare-up bright red and he would start to scratch them almost nonstop. Sometimes this would progress to an overt ear infection and other times it would go away on its own after a day or two. Avoidance was the key to management of his allergies.
People with food allergies on the other hand can develop life-threatening and potentially fatal anaphylaxis when exposed to an offending food protein and because of this on January 1, 2006, the Food Allergen Labeling and Consumer Protection Act (FALCPA) went into effect in the US. This required human food manufacturers to list not only the ingredients they intentionally added to a particular food or supplement, but any potential cross-contamination of outside ingredients that could occur during the manufacturing process. This is why you see labels that look ridiculously obvious like this…
But also ones with potentially hidden allergens like this…
Which brings me back to the study out of Chapman University on undeclared ingredients in pet foods. There are two ways that unlisted ingredient can find their way you’re your pet’s food:
- #1: The less sinister explanation is that this is simply a side-effect of the manufacturing process. The reality of pet food manufacturing is that one production line will process a number of different foods, potentially for different companies and brands on the same day. These manufacturing facilities do not close down and clean out the equipment between runs of different foods. A cleaning and sterilization process happens at the end of the production day and it would be too expensive, both from the cost of labor and lost production, to do it after every single food or treat run. Which means that if a “lamb and rice” diet follows a “chicken and rice” diet during processing, little bits of residual chicken will end up in the “lamb and rice” food. Additionally, if any powdered protein ingredients (i.e., “meals”) are in the recipe, small amounts of these powders can end up on the equipment. Think about what happens when you bake at home. I don’t know about you, but as careful as I try to be, I always end up with at least a little bit of flour on the counter (and me!). Cross-contamination of ingredients is a very common occurrence in OTC pet foods and treats and is one of the reasons why limited ingredient diets sold exclusively through veterinarians are more expensive. These prescription-only therapeutic diets are made in a way that prevents cross-contamination of other protein sources so that you as the caregiver know exactly what you are feeding.
- #2: The second reason undeclared ingredients may find their way into your dog or cat’s food is the more nefarious route, intentional (and illegal) substitution of ingredients. This means that the manufacture or raw material provider may have decided to use “Poultry” (a potential combination of chicken and turkey) as a less expensive alternative to individual “Chicken” or “Turkey”; “Chicken” as a less expensive alternative to “Beef”; or “Meat” (a potential combination of beef, pork, lamb, and goat) as a less expensive alternative to individual “Beef”, “Lamb”, or “Venison”. I’m not saying that this happened with any of the foods tested in this study nor that it happens at all in pet food manufacturing, but if I’m being completely cynical I think it would be fairly easy to pass off one non-descript animal protein ingredient for another. “Poultry meal” (a yellowish-tan powder) looks a lot like “turkey meal” (another yellowish-tan powder); “meat” (reddish-brown muscle protein) can look a lot like “venison”, “beef”, or “lamb” (all reddish-brown muscle proteins). When I look at the details of the DNA results in this article I noticed that a few diets that listed “Turkey” as an ingredient also tested positive for chicken and vice-versa; a few with “Beef” as an ingredient also tested positive for pork, lamb, and/or goat; and one that listed “Venison” was found to have no venison at all. Some of these may have been unintentional cross-contamination that occurred during manufacturing, while others (like the absence of venison in a diet that listed venison) may have been a purposeful substitutions. Irrespective of whether these were intentional or not, this study highlighted some of potential gaps in quality control of the OTC pet food supply chain.
For caregivers who are living with dogs and cats with food allergy, having undeclared proteins can lead to unnecessary discomfort and pain for the dog or cat as well as unnecessary medication and visits to the vet’s office. Allergen warning labels are not required on foods and treats for dogs and cats, so if you want to know what is potentially in your dog or cat’s OTC food, you need to look at every single product that particular brand sells and mentally add them to the List of Ingredients. The veterinary therapeutic diets are easier to figure out; what’s on the List is what’s in the food. Every pet food company big or small is trying to make a profit, the challenge is figuring out which ones are also trying to improve dog and cat health and which ones are solely trying to claim a piece of the $20 billion a year prize.
Lisa P. Weeth, DVM, MRCVS, DACVN