Happy fall, everyone! Although it may still *technically* be summer, I’m already gearing up for my favorite season. This autumn will certainly be different than years past, but one thing 2020 has taught me is to enjoy what I can. That’s why I’m dedicating this post to food allergies in dogs, one of my favorite topics! Believe it or not, I’m not being sarcastic. Food allergies can be incredibly frustrating for dogs and dog owners. The dog’s itching, licking, or head shaking can keep them both up at night. There are often repeat ear infections and skin infections due to inflammation and itch-induced trauma. Sometimes there’s even chronic vomiting or diarrhea. These symptoms negatively impact both the dog and their owner’s quality of life and lead to many vet visits. Therefore, it’s incredibly rewarding when I can help by solving the underlying problem: a food allergy!

Up to 24% of dogs who visit the vet for skin issues have an underlying food allergy. Food allergies cause year-round symptoms, whereas environmental allergies usually cause seasonal flare-ups. A food allergy can develop in any dog at any age, but most are 1-3 years old when the symptoms first begin. Usually, the dog has been exposed to the same diet or ingredient for months to years before they develop this hypersensitivity reaction. The most common symptoms include itching (especially paw-chewing and bottom-licking), ear infections, and secondary skin infections. As I mentioned earlier, some dogs exhibit gastrointestinal symptoms including vomiting, diarrhea or soft stool, flatulence, weight loss, and increased frequency of bowel movements. 

Food allergies are caused by dietary proteins that cross the normal intestinal mucosal barrier. Sometimes, this can be due to a breakdown of that barrier caused by viral or parasitic infections which are common in young dogs. The body recognizes the food proteins crossing the barrier as foreign and triggers an immune response. The most frequently reported causes of food allergies are beef, chicken, lamb, and wheat. This is probably because these are the some of the most common ingredients in dog food!

So, how do we diagnose a food allergy? Well, as you already know, we may be suspicious based on the dog’s symptoms and even their age. Usually we start by ruling out simpler issues first, such as fleas, mites, fungal skin infections, gastrointestinal parasites, etc. depending on the symptoms. It should be noted that normal dogs have occasional ear, skin, or gastrointestinal problems without having a food allergy. Therefore, it’s when these problems continue to reoccur or persist that we should consider an underlying food allergy. It’s important to understand that while we’re addressing the food allergy, we simultaneously need to treat any secondary problems such as a yeast or bacterial infection of the ear(s) or skin, because they can continue to perpetuate the symptoms. The same goes for itching, I aim to provide the dog with itch relief right away to break the itch/scratch cycle. This can be accomplished with oral or injectable medication. Next, we may initially start some anti-nausea or anti-diarrhea medication as needed to keep the pet comfortable. Finally, before trying to diagnose a food allergy we may decide to do blood work or other diagnostics to rule out other underlying health issues. 

As for food allergies, unfortunately no blood, saliva, or hair test has been proven to be diagnostic. The gold standard is an 8-12 week food trial, which takes commitment! The food trial is a diagnostic tool. If the dog has a food allergy and the food trial is done right, any gastrointestinal symptoms typically improve within 2-3 weeks and 90% of dogs with skin issues improve within 8 weeks. Exciting!

Do you want to learn more about the food trial and what happens afterwards? Stay tuned for part 2 where I’ll explain, in excruciating detail, the food trial… and beyond! 

Written by Dr. Maggie Schroeder – Columbia City Veterinary Hospital

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