One of the most frequent complaints I hear from dog owners is that their dog’s constant itching is never fully addressed by the vet. People are frustrated that no one ever figures out exactly what their dog is allergic to. Or, they are tired of having to give their dog medication all the time to keep the symptoms at bay. Often, they are irritated that every time they finish clearing up a skin or ear problem, the issue just comes back again within a few weeks or months.

We get it. It IS super frustrating when your dog has chronic skin problems. The constant licking and scratching, the constant stinky skin, the expensive vet visits… It’s a lot to handle!

You’re not alone. About 10% of dogs suffer from allergic dermatitis. Things are worse here in Texas since we don’t have intensely cold winters that normally eliminate airborne pollens, irritants, and fleas.

So let’s tackle some of the frustration out there. We’ll first try to answer some of these nagging questions about why dogs get allergies and what can and should be done about it; then we’ll talk a little about how it’s treated.

What are dogs allergic to? There are three major culprits: fleas, food, and seasonal allergens. Here’s how you figure it out:

Fleas: First of all, all dogs in Texas should be on a monthly flea prevention. That’s right. Every dog, every month! Just because you aren’t seeing fleas or getting bites doesn’t mean you don’t have fleas. At low levels, they can hide in your dog’s hair and in your house, and they will only bite people if you have a severe infestation. Dogs with allergic dermatitis especially need to take monthly flea prevention. That said, true flea allergy dermatitis presents with intense itching and/or hair loss over the rump. If your dog’s skin is worst in this area and you aren’t giving flea prevention – it’s probably fleas! In addition to looking for adult fleas, you can check for “flea dirt,” small black pieces of debris at the base of the hair shafts that turn water pink if allowed to sit (because it’s digested blood in the flea’s poop.) If your dog is highly allergic to fleas, a couple of bites may be enough to trigger the problem, and that’s a low enough flea burden that there may not be any evidence of the little buggers left behind.

Flea allergy dermatitis is the easiest to treat. Once you get your dog on a monthly flea preventative, the symptoms typically get a lot better. If your dog is severely affected, the vet may need to prescribe medication to calm the skin down as well.

Food: Food allergy is a bit mysterious and can be challenging to diagnose. Dogs with food allergies typically have year-round symptoms. They are also more prone to ear infections and/or anal gland disease. Sometimes, they also have gastrointestinal symptoms as well. If your vet suspects a food allergy, a hypoallergenic food trial will need to be performed. While there are commercially available blood tests for food allergies, most dermatologists still prefer a standard food trial, in which you feed your dog a special diet to see how the symptoms respond. Depending on your dog’s history, the vet’s preferences, and the current availability of these diets, the vet may either recommend a novel/new protein diet or a hydrolyzed protein diet. A novel protein diet requires feeding your dog something they’ve never eaten before. This can be a challenge, and sometimes we worry about cross-reactions (a dog with a chicken allergy may cross-react to duck). In addition, during the COVID-19 pandemic, novel protein diets were harder to find, so many vets now reach for hydrolyzed protein foods. Hydrolyzed proteins are protein molecules that are broken down into such small pieces the immune system no longer recognizes them and mounts a response/allergic reaction. There are only a handful of diets that vets typically recommend, and they are pretty expensive. Why? First, sourcing novel proteins and creating a hydrolyzed protein are not cheap processes. Second, the foods must be manufactured to ensure their purity (unlike typical commercial dog food, where it wouldn’t matter if a little piece of kitten kibble ends up in your dog’s bag of food). It’s like a candy bar warning someone with a peanut allergy that the product was manufactured in a plant that also processes peanuts. Even if the candy bar doesn’t contain any nuts, if you are severely allergic, even a small amount of cross-contamination can trigger a response.

Once you have your big bag of expensive dog food, you should transition your dog onto the new diet over the course of a week to gently acclimate the gut to the new food. After a week, when your dog is eating 100% of the new food, the food trial officially starts. Now, you must feed your dog the test food for about eight weeks and monitor for a response. Your dog can’t have any other pet food, table scraps, treats, or even flavored medications during this time. Often, your vet will also be treating your dog’s symptoms and having you come back for regular checkups to ensure the food trial is being followed and other confounding issues are addressed. For severely food-allergic dogs, the response to the new food can sometimes be obvious and fantastic! These are my favorite cases. For someone who has been dealing with their dog’s constant itching and ear infections, finally getting relief is enjoyable! In other cases (especially dogs with both seasonal and food allergies), the response can be a little less obvious. If it’s unclear if your dog has a food allergy at the end of the trial, your vet may recommend going back to the previous diet as a challenge, then monitoring closely for worsening symptoms. It’s critical during a food trial not to cheat on the diet. Technically, if your dog gets into another food source or gets a treat, the food trial starts all over again on day one. It’s also important to use the food recommended by your vet, and not something you buy over the counter, if possible. We want to use the purest food available for the food trial because we’re using it as a diagnostic tool. If you use something you buy over the counter and it doesn’t work, we really don’t learn anything from the food trial.

Seasonal aka environmental aka inhalant allergens: This is the “everything else” category for dog allergies. Cedar, oak, ragweed, grasses, molds, dust mites, etc., all fall into this category. Here in Central Texas, there always seems to be some allergen at high levels at some point during the year. Dogs with seasonal allergies tend to have waxing and waning symptoms and periods of the year when they are consistently worse. However, given the nature of the location, even dogs with seasonal allergies may have year-round itch. Seasonal allergies tend to present more on the parts of the body that are near the ground (feet, armpits, belly, groin). Paw chewing/licking is very common. So, if you suspect seasonal allergies in your dog, should you get them allergy tested? Well, it kind of depends. See, allergy tests can give both false positive and false negative results. For most dogs, the information gained doesn’t really help you much, either. Pollens can travel on the wind for miles, so even if you know your dog is allergic to oak, you can’t get rid of all the oak pollen in the environment. The real benefit of allergy testing is for creating “allergy shots” or immunotherapy.

Now, let’s talk about diagnostics. It seems the vet staff is always running tests, but none of them ever get to the bottom of what the dog is allergic to. Why is that?

Several tests may be needed to rule out other causes of itching, like mange or secondary skin infections. Dogs that have infections as a result of their allergic dermatitis need to have these infections treated, as they are also contributing to the redness and itch. To ensure that the treatment will be effective, your vet may want to look at material from the ears or on the skin’s surface to determine which microbes are involved and which medications will resolve the problem.

Allergy testing (discussed above) can be performed if you are considering immunotherapy. Blood or skin allergy tests are available to help determine which pollens your dog should be treated for. Using the test results, dilute amounts of the allergens are introduced to the body at regular intervals to slowly train the immune system to stop mounting a response. The immunotherapy (aka allergy shots) needs to be adjusted based on each individual patient’s response and typically takes about a year to see results, so I normally refer my patients to the dermatologist for this service to ensure they will get the best possible results.

So why does my vet always send me home with a dozen different medications? Good question. The best way to treat allergies is with a multimodal approach, meaning we normally need to use multiple medications together. Drugs like steroids, Apoquel, and Cytopoint injections are used to decrease the underlying inflammation and itch. Antibiotics, antifungals, and topical antimicrobials treat and prevent skin infections. Omega fatty acids and antihistamines decrease inflammation. Regular baths and ear cleanings remove pollens, bacteria, and yeast from the skin surface, and some can even help repair damaged skin.

My dog got better after the last vet visit, but then the problems came right back again! Most dogs with allergic dermatitis are going to have this disease for their whole lives. If the symptoms are severe enough, seeking the help of a veterinary dermatologist may be in your best interest. Immunotherapy is the only definitive way to alter the disease process. Most dogs will need to be on long-term medication to manage their symptoms. I normally try to start by calming my patient’s skin down and work to determine the underlying cause first. Once the patient is feeling better, we try to talk about long-term management to prevent recurrence. If you’re frustrated with your pet’s allergies, make sure you tell your vet that you are interested in coming up with a long-term strategy. If you let your vet know you’re on board for the long haul, they can help you come up with a plan that works for you, your dog, your lifestyle, and your wallet!

This article is meant to provide general information about pet health topics and should not be considered advice for your specific pet. Only patients with a valid veterinary-client-patient relationship can be diagnosed and treated by Dr. Miller in the state of Texas. Dr. Miller strongly recommends that you consult with your veterinarian about your pet’s health concerns.


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