How to tell if your dog has a food allergy

You’ve kept your dog treated and protected from fleas. You’ve tried both conditioning and medicated shampoos, and even tried sneaking herbal supplements for healthy skin into his diet. Still, your dog spends a great deal of his time scratching, licking, chewing, and rubbing his face on furniture, leaving you wondering what’s wrong. Many pet parents focus on treating symptoms like itchy skin in their dog with topical treatments, and don’t consider the possibility that the mix of symptoms they are seeing in their furry friend is related to his diet. However, just as people, dogs can have food allergies that range from mild to severe.

Food allergies can develop over time

From the time you first brought home your puppy, you’ve done the research and gotten him the best puppy food you could find. You make sure he gets plenty of playtime and exercise, and you enjoy long walks together. Most dog owners put in the work to be responsible and loving pet parents. But symptoms of food allergies in pets can be difficult to pinpoint. This is partly because they often don’t manifest symptoms immediately. The same food you’ve fed your dog for years can be well tolerated at first, but your dog may develop an allergy to it that can be difficult to identify. Left unprotected, your dog’s symptoms can worsen over time and even lead to behavioral changes.

Common allergen triggers in dog foods

Dog food allergies occur when a specific protein contained in the food triggers a dog’s immune system to attack it as an outside invader, triggering noticeable symptoms. The most common proteins which cause allergic reactions in dogs are from specific proteins found in beef, chicken, eggs, and dairy, with beef being the most common allergic trigger. Beef has been identified as the culprit in 34 percent of allergic reactions in dogs, followed by dairy at 17 percent and chicken at 15 percent. Multiple food allergies are also common. One-third of dogs diagnosed with a food allergy are found to be allergic to more than one ingredient in their food.

More rarely, dogs may have an allergic reaction to fillers found in dog foods such as wheat, corn, and soy. Often pet owners misidentify their dog’s allergy as a reaction to the grain fillers in their food, because humans more often react to those ingredients. In dogs, however, grain allergies are rare. It is much more likely to be a protein allergy causing symptoms in your dog.

Gelatin is another food allergy trigger for some dogs and can be difficult for owners to identify. Dogs are typically exposed to gelatin when given medications and supplements in capsule form. Owners may mistakenly assume the medication or supplement is the trigger, when it’s more likely to be the gelatin in the capsule it comes in.

It’s also important to note that some dog foods have tested positive for proteins that are not listed on the label. This is often the result of multiple types of meat for dogs being processed in the same equipment.

Symptoms of dog food allergies

While a dog food intolerance may develop symptoms over time, an allergic reaction is more likely to occur suddenly, with itchy skin, and sometimes skin and ear infections. An allergic dog may also have vomiting and diarrhea. Unlike food intolerance, which causes weight loss and gastrointestinal disorders, a true allergic reaction in a dog almost always causes itching and sometimes visible rash on a dog’s skin. Itching from food allergies commonly causes a dog to scratch excessively at the face, feet, ears, forelegs, armpits, and anus.

Other symptoms that your dog may be suffering from a food allergy are hair loss, inflamed skin, rash, hives, open sores, odor from ears and feet, coughing, wheezing, shortness of breath, head shaking, red swollen ears, sneezing, runny nose, or red, runny eyes. More rarely, your dog may experience swelling of the face as a result of a food allergy.

Anaphylaxis in dogs

Dogs may suffer allergic reactions that trigger anaphylaxis if their food allergy is particularly severe. Anaphylaxis may occur the first time your dog encounters a new food, or if they’ve been suffering lesser reactions for some time and they become more sensitive. In dogs anaphylaxis most often affects the liver first, causing severe stomach upset with vomiting and diarrhea. Unlike humans, dogs suffering anaphylaxis don’t always swell or experience difficulty breathing. Dogs with this severe allergic reaction may have symptoms in addition to stomach upset, including such symptoms as drooling, pale gums, cold limbs, increased heart rate, wheezing, difficulty breathing, seizures, shock, and coma.

Anaphylaxis reaction in dogs can be caused by ingredients in foods or by vaccines, medications, or insect stings or bites.

Treating food allergies in dogs

Once your dog’s veterinarian confirms that your pet is suffering from an allergic reaction, the next step is to identify the trigger. Your veterinarian may put your dog on a special elimination diet. This may involve feeding your dog a prescribed dog food with the proteins broken down to the point of not being able to cause reactions. After being on this food for a month in order to clear the dog’s system of all traces of the offending protein, you may be instructed to introduce one new food ingredient per week and watch your dog for reactions. This may continue even after you’ve identified an allergen in case your dog has more than one trigger.

After you have identified the substances your dog is allergic to, you will have to carefully read the labels of any food you give her. There are some great dog foods for allergic dogs, but you will have to ensure that the food you choose does not contain your dog’s particular allergens.

Be particularly careful not to be fooled by statements on the front of the bag, such as “Lamb Flavored.” If a dog food is labeled as “flavored” with an ingredient, it means the main protein source is something different. Lamb-flavored food may contain mostly chicken or beef.

Treating anaphylaxis reactions in dogs

Anaphylaxis in dogs is a medical emergency just as it is in humans. Your dog will need to see a veterinarian or be taken to a veterinary hospital or clinic immediately. Your dog will probably be given an injection of adrenaline, followed by treatments with antihistamines and hydrocortisone. Oxygen and intravenous fluids may also be administered to help stabilize her. You may be prescribed an epipen injector for your dog in case of accidental exposures in the future.

While having a pet with food allergies can present an initial challenge, once you’ve identified the triggering allergen in your dog, diligence in her diet is usually all it takes to keep her well and happy. And a happy pet means a happy home!


Resources— Pets WebMD, NomNomNow, Dogtime