Just like in humans, your dog can develop allergic reactions to its food. The exact ingredients they're reacting to can be tricky to pinpoint. But once you've gotten familiar with the symptoms to look out for, some smart detective work by you and your vet will help you land on a plan to ease your pup's discomfort.
First, let's clarify what we mean by a food allergy, rather than a food sensitivity or intolerance: When your dog has an allergic reaction to an ingredient in its food, its immune system releases antibodies to fight off the unwanted substance, resulting in itching, hot spots, and other symptoms. A sensitivity, according to the American Kennel Club, doesn't involve the same immune response. About 20% of all dogs will develop a reaction to food that results in itchy skin and 40% will show signs of an allergy before they’re a year old, says Adam P. Patterson, DVM, Diplomate of the American College of Veterinary Dermatology, Chief of Dermatology at Texas A&M University. German shepherds, Labrador retrievers, and West Highland white terriers tend to be the most commonly affected, but allergies can develop in any pup, purebred or otherwise.
Unfortunately, there’s no way to predict an allergic response to ingredients in your pup's food or treats, but paying attention to your dog’s behavior is an important clue to uncover and treat any problems. It’s worth noting that your dog can also have seasonal or environmental allergies—one clue to isolate that the issue may be food-related is if symptoms are present year-round. Regardless, your first step is to consult your vet to come up with a treatment plan.
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Common Dog Food Allergy Symptoms to Watch For
Detection can be tricky, as signs overlap with those of seasonal or environmental allergies. Here are three to keep an eye on, and how to spot the difference.
All dogs scratch themselves, but allergy-related itching is unrelenting and nearly constant. Natalie Theus, DVM, MS, Diplomate of the American College of Veterinary Dermatology, says the most common sign of a food allergy in a dog is itching, which can manifest as rubbing, licking, scratching, and/or chewing different areas of the body. "Pet owners may notice itching of the perianal (rear end) area, paws, around the mouth, the armpits, and/or the groin,” Theus says.
2. Hot Spots
If you notice your dog has chewed on one spot so often and badly that it looks like a wound, that area is called a hot spot, which is “a sudden onset of moist and focal bacterial infection caused by self-trauma,” Patterson says. Unfortunately, hot spots can lead to a skin infection if left unchecked. Be sure to ask your vet how to treat these, and inquire about a potential allergy.
3. Ear Infections
There’s a difference in the occasional ear infections your dog can get from swimming and persistent infections due to food allergies. “The ear canals can become inflamed from the allergic inflammation in the skin,” Theus explains. “This will lead to overgrowth of the normal microorganisms (yeast, bacteria) that live in the ear canals.” She says you may notice the pet scratching at his or her ears, unusual head-shaking, odor, or excessive earwax or discharge from the ears.
How Are Dog Food Allergies Diagnosed and Treated?
If you suspect your dog has an allergy, simply changing its brand of food or flavor isn't enough (many pet foods are made with similar proteins and grains). Your best move is to make an appointment with your vet. Patterson explains the gold standard test for diagnosing a food allergy is an elimination diet trial over a period of several weeks. During this time, the vet will work with you to gradually eliminate and then reintroduce ingredients that may be causing irritation. Despite widely accepted myths, grains are not always the leading culprit of pet food allergies. Instead, animal proteins like beef or chicken along with dairy and egg can be to blame. Because of this, a diet like Purina ONE SmartBlend Lamb and Rice may be recommended.
Remember, it's important that only the vet-approved diet is fed during this time. Accidental exposure to non-allowed foods—wrapping other medication in cheese or bologna, the feeding of another pet’s food in the household, children dropping food from the high chair or table, household visitors giving table scraps—can all interfere with your investigation, Patterson says, so it's important that all household members are on board with this trial, for your pup’s sake.