Forget fleas; it may be allergies!

By Dr. Beth Leermakers

My new foster dog is very uncomfortable, constantly scratching her ears and licking and chewing on her paws. Without spending a fortune on diagnostics (rescue group budgets are limited), it’s difficult to know what’s causing her itchiness. Because she isn’t infested with fleas, I suspect that Minnie’s skin issues may be caused by a food allergy.

Food allergies occur when the dog’s immune system responds inappropriately to something (usually a protein) found in the diet. The immune system treats this perfectly innocuous substance (e.g., chicken) as a threat, overreacting to it. 

Food allergies are uncommon, affecting only 0.2 percent of dogs, according to the 2018 State of Pet Health Report from Banfield Pet Hospital. Therefore, it’s important to consider other causes for your dog’s symptoms. Some breeds — Labrador Retrievers, Cocker spaniels and West Highland White Terriers — have a higher risk of food allergies. 

Reasons to Suspect a 

Food Allergy

People may assume that food allergies lead to gastrointestinal issues, but an upset stomach may or may not be a sign of a pet food allergy. Instead, skin problems are the most common symptoms of a food allergy. This makes sense when you think about how people react to a food allergen (e.g., hives or a skin rash). 

Symptoms of food allergies include:

• Chronic itchiness (most often on the paws, face, ears, belly and under the tail)

• Hair loss 

• Skin lesions (especially when the dog is harming himself while trying to scratch the itch)

• Frequent skin infections 

• Frequent ear infections

• Licking or chewing the feet 

These symptoms may be caused by environmental allergies to triggers like pollen, mold or house mites, but these allergies tend to be seasonal. 

Dog food allergies can develop at any time. Your dog may suddenly become allergic to the food she’s been eating for years, or she may show symptoms shortly after you switch to a new food. 

Diagnosing a food allergy isn’t quick or easy. There is no simple allergy test to tell you if your dog has food allergies and, if so, what she’s allergic to. Instead, you must start at the beginning and use the process of elimination. 

Rule out other medical conditions. Given the low prevalence of food allergies in dogs, it’s highly likely that something else may be going on. Your veterinarian will conduct tests to determine whether your dog’s skin problems are due to conditions with similar symptoms such as flea infestations, mange, ringworm, yeast infections, bacterial infections or environmental allergies.

If there is no other cause for your dog’s itchy skin or ear infections, your vet may start to suspect that food allergies are to blame. It’s time for a food trial to test that hypothesis. 

Start an elimination diet trial. Your dog will eat a prescription diet and nothing else (no table scraps, no treats unless they go with the prescription food) for about two months, to see if the itchy skin or ear infections resolve. If the issues resolve, the next step is to reintroduce the original food to see if the symptoms recur. If the itchiness or ear infections return, your dog has a food allergy. 

Do you have to use a prescription (read: expensive) diet for the elimination trial? Yes, if you want the results to be accurate. 

Up to 83 percent of over-the-counter diets that claim to be “single protein” or “limited ingredient” have been found to contain ingredients not listed on the bag, so they can’t be reliably used for an elimination diet trial.

Changing your dog’s diet is the only way to successfully treat a food allergy. Protein sources (not grains) are usually responsible for allergic reactions. The top three most common causes of food allergies in dogs are beef (34 percent of dogs with food allergies), dairy (17 percent) and chicken (15 percent). Other ingredients that may trigger allergies include wheat, soy and eggs. 

Sorry Minnie, those yummy chicken jerky treats have to go. 

The new food may include: Novel proteins. One way to avoid an allergic reaction is to feed your dog less-common proteins that she has not been exposed to before. Novel protein diets replace chicken or beef with rabbit, venison, fish, duck and other ingredients rarely found in commercial dog foods. 

Hydrolyzed proteins. These diets break proteins down into such small amino acid chains that the immune system doesn’t recognize the original protein source, reducing the likelihood of an allergic reaction. 

I’m switching Minnie to an over-the counter sensitive skin diet (to be determined). Hopefully she’ll get some temporary relief until her future adopter can investigate her allergies further.