Have you noticed your dog spending more time scratching at night? How about excessive shedding? Have they had recurrent ear infections? Surprisingly common, adverse reactions to food can cause your pup to become uncomfortable and eventually lead to serious skin disease.
Although experts currently disagree about the exact number, an estimated 17% of dogs with chronic skin disease are thought to have allergies to food. That’s quite a large portion of the dog population when you consider that veterinarians see itchy dogs on a daily basis!
What does a food allergy look like?
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Symptoms of food allergies are variable. They can range from mild all-over itchiness to:
- Hair loss—especially around the eyes, belly, feet, and anus
- Non-seasonal pruritus (itchiness)
- Bacterial or fungal skin infections/rashes
- Chronic or recurrent ear infections
- Digestive upset—diarrhea and/or vomiting
No known breed or sex predilection has been documented…it can happen to anyone! Age seems to play a part: Young dogs (less than one year of age) and those older than 6 seem to make up the bulk of food allergic patients.
It’s important to note that combination allergies can occur too. Atopy, the term used to describe sensitivities to substances like pollens, molds, and dander, is also common in the canine world. This is because when the body mounts an allergic response to one substance, other allergies commonly develop.
Common Misconceptions of Food Allergies
- Contrary to what many believe, allergies to corn and wheat are rare in dogs. Far more common are allergies to the protein sources in the food: chicken, beef, lamb, fish, soy, etc.
- Just because a dog has eaten the same food for a long time without a problem doesn’t mean he/she won’t develop an allergy to that food in the future. The body has to be exposed to a food to develop an allergy to it.
- Rotating foods throughout a dog’s life won’t necessarily prevent food allergies. Recommended reading: Blog article “Does Food Rotation Prevent Allergies in Pets?”
- While choosing a good-quality diet is always in your dog’s best interest, this won’t necessarily prevent a food allergy. If your dog is allergic to chicken, for example, even a top-tier, ultra premium diet containing chicken will still cause your dog problems.
Diagnosis and Treatment
First and foremost, your veterinarian needs to thoroughly examine your dog and rule out all other causes of skin disease (fleas/mites/lice, systemic illness and autoimmune disease to name a few), then discuss with you how best to proceed.
Blood and skin tests for allergies exist, but the best and most accurate method to “rule in” a food allergy is to do an 8-week elimination diet. This means feeding your pet a hypoallergenic diet with a single protein source that your dog has not eaten before. This means NO: people food, non-approved treats, fallen toddler Cheerios, bank-teller cookies, or stolen cat food snacks for a full 8 weeks. (As you can imagine, this is easier said than done)!
Commercial diets—available by prescription only—are usually the simplest way to go. Over-the-counter limited ingredient diets exist, but use caution if going this route. Most of these diets are manufactured in facilities that make many types of diets and the equipment may have residues from other proteins. This will complicate the diet trial results. The third option is home cooking a diet for the 8-week duration. If you’re up for this, great! But please get your vet’s guidance to make sure it is complete and balanced.
If the dog’s symptoms improve over the 8 weeks, then the trial is a success! We have confirmation that the food was indeed the problem. The owner can then opt to stay on the hypoallergenic diet indefinitely or gradually transition to a new food, free of the proteins of previous diets. To further confirm the allergy, dermatologists recommend “challenging” the dog by re-introducing the protein (or proteins) and watching for relapse. Honestly, most owners I’ve worked with prefer to skip this part. They are just happy that their dog is feeling better!
The 8-week elimination diet is labor intensive but well worth the hassle in dogs with suspected food allergies, and completing a diet trial can greatly improve an allergic patient’s quality of life.
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Vet Rec. April 2001;148(14):445-8