Several of my personal dogs have struggled with allergic reactions to their food and I’ve lost count of how often this problem popped up in the veterinary clinics I have worked in. They can be incredibly disruptive for both you and your dog – your dog may be constantly itchy or have persistent stomach upset and you end up stressed and worried not only about how they feel but also about cleaning up after any unfortunate incidents. Our furry friends are unfortunately susceptible to many common dog food allergies but these can often be overcome and controlled with strict attention to diet.

Big dog

What Causes Allergies?

Technically speaking, an allergy is an immune response by the body to something it has become hypersensitive to. The two most common manifestations of food allergies are skin issues and digestive upset and I will go into those more below. Unfortunately, determining if your dog is experiencing an allergic reaction and then narrowing down exactly what has caused the sensitivity can be extremely difficult.

If your dog’s food allergies cause skin problems, these will most likely present as severe itchiness and it can literally drive a dog to distraction. Hair loss, dull skin and coat, and skin lesions can also be present. Unlike bacterial or fungal infections, the itchiness caused by food allergies cannot be treated with topical solutions. Instead, the root cause of the allergy must be determined and eliminated. Secondary bacterial infections of the skin can be a problem if your dog scratches enough to damage the top layers of skin.

In addition to causing skin problems, food allergies can also cause digestive upset. This can be nausea or vomiting or diarrhea. Vomiting can occur on or more times a week and usually happens about 1-2 hours after eating. Like the skin problems however, these symptoms can be caused by many other things.

Food Ingredients That Cause Allergies

Dry dog food

So what exactly triggers all these annoying symptoms? Usually it’s a protein and which protein or proteins your dog is sensitive to will likely be determined by his genes. Sensitivity to ingredients containing these proteins trigger an immune response that causes inflammation in the intestines and skin. In dogs, the most common culprits are beef, chicken, soy, wheat, corn, and milk. Each dog can be sensitive to anywhere from 1-5 ingredients.

Diagnosing Food Allergies

In order to be certain that your dog is suffering from allergies you first have to rule out other contributors to skin and digestive issues. Skin issues can be caused by fleas, other insect bites, bacterial infection, fungal infection, or simply a reaction to something in the external environment (like shampoo or maybe even the fertilizer you just used in your yard). Digestive upset can be caused by spoiled food, ingestion of a foreign object, ingestion of poison or toxic materials, or simply a mild bacterial overgrowth in the gut.

Unfortunately there is no reliable diagnostic test for food allergies aside from a strict elimination diet. So, once you have ruled out the other common contributors to skin and digestive problems it is time to begin focusing on determining the foods your dog is allergic to. To start, you will want to drastically reduce the protein in your dog’s diet and feed him only ingredients that he has not yet been exposed to. For example, if you have fed a diet consisting of beef for protein and corn for carbohydrates then you will want to eliminate these completely and find a diet with completely novel sources of protein and carbohydrates such as lamb and rice.

This trial diet can be fed for up to three months. If there is a marked improvement in your dog’s symptoms then it can be assumed that a food allergy was present. To truly confirm a food allergy, you can reintroduce previous foods to the diet. If a reaction occurs – which usually happens around three days to two weeks after the introduction of the offending food – then the presence of a food allergy is confirmed and the dog should be again placed on the trial elimination diet until symptoms resolve.

If you want to determine which exact ingredient caused the allergy, you can introduce individual ingredients one by one and wait for a reaction to occur. If this is not something you are interested in then you can simply refrain from feeding your dog any of the ingredients that were in his previous food.

A Note About Switching Foods

Be prepared for this process to take some time. It is never a good idea to switch from one food to another quickly – this almost guarantees stomach upset for your dog. Instead, replace the old food over several days by mixing it with the new food. For the first couple of days mix on part new food to three parts old food, then try a couple of days at two parts new food to two parts old food, the another couple of days at three parts new food to one part old food, and finally, only feed the new food.

Don’t Forget the Treats!

If you feed your dog treats, even if it’s only occasionally, you have to include them in your elimination diet or you will not achieve any results as you change foods. If your treats contain beef and rice and these are ingredients you are trying to eliminate then search for new treats that are free from any ingredients your dog received previously. This may require some effort but it is crucial to be consistent with the ingredients in both treats and food (and even table scraps if you feed those) otherwise you will be inadvertently sabotaging your own efforts.

Last But Not Least

Dealing with food allergies in your pet can be extremely frustrating but stick with it! Once you reach the point where you find the culprit (or culprits) and make the necessary adjustments, the relief you will see in your dog make it all worth it. My dog was eventually completely symptom free on a strict lamb and rice diet. And don’t forget that if you find this too overwhelming to deal with and keep track of by yourself, you can always enlist the aid of your veterinarian. Food allergies are common enough that many veterinarians are well acquainted with methods to detect and treat them and they may have access to or recommendations for commercially produced specialty diets that are hypoallergenic.