How can you tell if my dog has a food allergy?

The only way to test for a food allergy is to do an elimination diet trial. You can home cook food, which is probably the purest form of doing that. And we would help you to formulate a diet. We also use a couple of effective commercial diets. The most crucial thing is when we do a food trial, you cannot feed anything else because that could contaminate and ruin our results. We generally would put a dog on a diet for a minimum of six weeks. And if we see the symptoms get much better, that's great. Unfortunately, many dogs that have food allergies also have other allergies, so it may be a combination of things. In general, though, a food allergy is a smaller component of what most dogs experience, but it can be a very significant one for those that have it.

Food allergies are relatively common. We'll go over the detailed history and see if your dog has had skin and ear issues before. Then we will also go over what the diet is typically for your dog. Usually, it's going to be based upon the history and then also doing a food trial. Switching your food around will not cause an instant change. It takes a good eight to 12 weeks for your dog to have all those proteins taken out of their system. We see if your dog will respond by switching your dog's food up using over-the-counter dog foods. That's generally not going to cut it. It's usually prescription-type dog food, and they have to be on this food trial for eight to 12 weeks solely before we can say definitively that your dog has a food allergy.

This is really important because I see this a lot with clients. They think their dog might have food allergies, and they use Dr. Google to try to discern what's going on. They then start switching their dog's food to various over-the-counter types of foods. That can potentially cause more problems in the long run because it exposes them to different proteins, which makes it harder to discern what the issue is.

The right way to identify a true food allergy, which is common in dogs, is to do what's called an elimination diet. That can be done in two different ways. The first is with a hydro protein diet, a prescription diet specifically created with the protein molecules broken into smaller pieces. That's what they mean by hydrolyzed. The pieces of the protein kind of go under the immune system's radar. The hope is that the immune system doesn't recognize them as foreign proteins leading it to respond negatively. This is the most common type of food trial we do because those foods are the most consistently readily available, and they tend to work really well.

The other type of food trial that can be done is called a novel protein food trial, which entails giving a protein that the dog has never been exposed to before. This can be challenging, and we'll have to make a thorough diet history. 10 years ago, people used kangaroo meat for this trial. I don't think it's used as much anymore because of the supply issue, but that would be a protein that dogs have never been exposed to before.

So we put them on a certain main protein to see if we can get the immune system not to respond to it. Both food trials are trying to find out what the immune system will be happy with. Other critical things to consider before you go with any one of these routes include that it is ideal if these are prescription-level diets. Because they are formulated specifically for this purpose, they undergo quality control to minimize or eliminate cross-contamination. This can really only be guaranteed on a prescription level. So prescription diets are definitely the best way to go when we're working through a food allergy. The other two big considerations are firstly making sure your pet ingests no other food when they're in the trial period, which typically lasts for eight to twelve weeks. Ensure they eat nothing but the specialized diet, no food dropping on the floor, no human food, and no eating other dogs' food. Just the specialized diet food, so that we can eliminate everything else.

At the end of that food trial of eight to twelve weeks, we reintroduce the old food for over a week in duration, although we don't always do this. This is the best way to definitively diagnose a food allergy. If the dog has a significant food allergy and has been doing much better on the new food, they will start responding negatively when the old would is reintroduced. That's how you definitively diagnose a dog with a food allergy. It's simple, but there are steps you have to follow in order to do it adequately, which can sometimes be a challenge.

Food allergies typically cause reactions in the skin. You would think that a common reaction from food would be GI-related, like vomiting or diarrhea, but only about 20% of dogs with food allergies will have GI symptoms. Oftentimes they have dermatologic or skin conditions, primarily itchy ears with maybe no infections at all, just itchy ears and booties. They might scooch or lick around their bottoms. Those are the two most common areas that we'll see canine food allergies and general itchiness of their body. It's difficult to diagnose dogs with food allergies. Of all the dogs that have allergies, only a very small subset truly have food allergies. So you really do need to work with your veterinarian very closely, and we often do nutrition trials to make that final diagnosis.

A lot of times if we think that a dog has a food allergy, we're going to try a food trial by taking them off all of the main proteins and putting them on a specific diet such as ZD or Royal Canin's hypoallergenic profile or even Purina's hypoallergenic.