Dog Allergies: Causes, Symptoms and Treatment

By: Dr. Jennifer CoatesUpdated:

dog allergies - itchy dog

Dog Allergies: Causes, Symptoms and Treatment

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Watery eyes, sneezing, itchy skin, the sight of pollen in the air—anyone who suffers from allergies probably feels a sense of dread when reading those words. But can dogs have allergies, too? The answer is yes: Just like humans, canines can suffer from dog allergies of their own.

Unfortunately, dog allergies are often tricky to diagnose and cannot be cured, only managed. And they’re more than just an annoyance for our four-legged friends. Allergies commonly result in secondary health problems, like recurrent skin and ear infections. One of my patients, a Lab we’ll call Sami, had a history of near constant ear infections that would flare back up every time his owners stopped treating him. Once we determined that Sami was allergic to the beef in his dog food and switched him to completely beef-free diet, his ear infections were a thing of the past.

Like people, dogs can have allergies to just about anything. First you need to figure out exactly what is causing the allergic reaction. Then, once you have a diagnosis, your vet can determine the best treatment plan for your pet.

Different Types of Dog Allergies

Veterinarians organize the most common dog allergies into the three categories:

  • Fleas
  • Food
  • Environmental allergens

Flea Allergy Dermatitis

Flea allergies are at the top of this list for a reason. Bites from fleas are the leading cause of allergic reactions in dogs. Many dogs are hypersensitive to flea saliva.

Just because you don’t spot fleas doesn’t mean they aren’t the culprit of your dog’s discomfort. Dogs do not need to be visibly infested with fleas to experience severe allergy symptoms. Just one bite may be all that is necessary. Itchiness and hair loss that is focused at the base of the tail strongly suggests fleas.

Dog Seasonal Allergies

Environmental allergens are probably what first come to mind when you think of allergies. They often start out as a seasonal affliction but tend to progress and may become a year-round problem with time. Pollen, dust mites, food storage mites and mold are all common dog allergens.

The inflammation and itchiness caused by environmental allergies make dogs lick and chew their skin to excess. In cases of dog eye allergies, the eyes might also become red and itchy. Some breeds, such as Boxers, Cocker Spaniels and Labrador Retrievers, are more susceptible to seasonal allergies, but any dog can be affected.

Dog Food Allergies

Allergic reactions to food ingredients are not as common as allergies to fleas or environmental triggers. However, food allergies are possible and can develop soon after starting a new food or after years of eating the same food. Symptoms are similar to what you would see with any other type of allergy, although they are sometimes combined with digestive problems, such as vomiting or diarrhea.

A study published in 2016 found that the most common triggers for dog food allergies are beef, dairy products, chicken and wheat. Many dogs, including my own, are allergic to more than one type of food.

Common Dog Allergy Symptoms

Dogs suffer similar symptoms regardless of the cause of their allergies, and allergies produce many of the same symptoms as do other diseases that affect the skin. This can make reaching an accurate diagnosis frustrating.

With all the allergy types, the primary symptom is itchiness. Dogs may rub their faces against the carpet, rub their sides along the wall, and scratch and gnaw at their skin. Sometimes itchiness is focused on particular locations while in severe cases, the whole body is affected.

Common symptoms of dog allergies include:

  • Repetitive scratching, licking and chewing of the body
  • Chronic or recurrent skin and/or ear infections
  • Head shaking
  • Hair loss, hot spots, scabs and other skin lesions

Bambi Edlund

Diagnosing Dog Allergies

Diagnosing an allergy can be a lengthy process because there’s no single test that will tell you all you need to know. Reaching a diagnosis and pinpointing the allergen(s) that are responsible for a dog’s symptoms takes time and patience.

Your veterinarian will take into consideration the results of a physical exam along with all the factors relating to your specific pet. Your dog’s age, breed, medical history, present condition and any recent changes made at home will all influence the way you proceed.

If fleas or “flea dirt” (flea excrement) are found, it could be a quick diagnosis, although this is not always as straightforward as you might think. I’ve had several owners refuse to believe that fleas were to blame for their dog’s symptoms until their dog’s itchiness disappeared after I was able to convince them to try a good flea control product, like Revolution Topical Solution for Dogs.

If fleas are not the problem, your veterinarian will probably need to run some simple diagnostic tests. The first step is typically to rule out other, common causes of itchy skin in dogs. Potential tests include:

  • Fungal cultures for ringworm
  • Skin cytology to diagnose yeast or bacterial infections
  • Skin scrapings to identify mange mites

If after all this your veterinarian thinks that an environmental allergy might be to blame for your dog’s symptoms, they may recommend dog allergy testing. With an intradermal skin test, a tiny amount of many potential allergens are injected into different spots in the skin, and your dog’s reaction to each is monitored to identify their triggers. Some veterinarians will refer you to a veterinary dermatologist for these kinds of procedures.

Blood allergy tests are another option, but they’re not generally thought to be as reliable as skin testing. They are easier to run, however. For this type of dog allergy testing, a sample of blood is simply sent to a diagnostic lab where it is checked for antibodies against a variety of allergens.

Should your veterinarian suspect dog food allergies are to blame, you’ll need to do a diet trial at home. Prescription foods are ideal during this process because they are much less likely to be contaminated with other ingredients than are in over-the-counter foods. A good option for food trials are diets made with hydrolyzed protein, meaning the protein is broken down into molecules that are too small to trigger an allergic reaction. Hill’s Prescription Diet z/d Original Skin/Food Sensitivities Dry Dog Food, for example, is made with hydrolyzed chicken liver. For dogs who do better on wet food, canned options such as Royal Canin Veterinary Diet Hydrolyzed Protein HP Adult Canned Dog Food are available.

Once all potential food allergens have been eliminated from your dog’s diet, you should see a marked improvement in their symptoms within four to six weeks, but some dogs are slower to respond. Many veterinarians recommend that a food trial continue for at least eight to 12 weeks. When your dog’s allergy symptoms have subsided, you can slowly reintroduce foods to see what triggers a reaction and to confirm the diagnosis.

How to Treat Dog Allergies

Once a dog has been diagnosed with a specific type of allergy, treatment can begin. Your veterinarian will decide how to treat your dog’s allergies according to the allergen or allergens. The most commonly prescribed treatment is Apoquel, which has been prescribed to 9 million dogs (and counting!) and is effective for flea allergy, food allergy, contact allergy, atopic dermatitis.

If fleas are the culprit, a veterinary-recommended flea treatment medication should be administered per label instructions. A deep clean of the home will also be required since at any given time the majority of fleas that make up an infestation live in the environment, not on your dog. Thoroughly vacuum your carpets, hard floors, and upholstery. Wash and dry (on a hot setting, if possible) all your and your dog’s bedding. For hard to reach areas, consider a premise spray like Advantage Household Spot & Crevice Spray.

Get more tips on how to combat fleas on dogs.

With environmental allergies, hyposensitization therapy is generally considered the gold standard for treatment. Dogs are given repeated injections or doses of a sublingual (under the tongue) serum containing the offending allergen(s) to desensitize the immune system. After a while, dogs build up a tolerance and become less reactive.

A variety of symptomatic approaches to managing environmental allergies are also available. Combination therapy tends to work best and may include:

  • Antihistamines for mild cases, although they are not very effective for dogs on their own.
  • Bathing your pet with an appropriate medicated shampoo, which will soothe the skin, regardless of the type of allergy. Douxo S3 PYO Antiseptic Antifungal Dog & Cat Shampoo for example, contains ingredients that help prevent or treat infection and relieve itching.

(For dog seasonal allergies, bathing has the added benefit of removing allergens from the coat and skin. It’s also helpful to keep windows closed and wipe your pet down when they come inside. Pay extra attention to the paws.)

  • Omega 3 fatty acid supplements, which improve skin health and are safe for most dogs. Vetoquinol Care Triglyceride Omega-3 Fatty Acid can be given orally via a capsule. You can also puncture the capsule and pour the liquid over food.
  • Oral steroids, such as prednisone. They provide quick relief, but can be associated with negative side effects when used over a long period of time. Many veterinarians will only prescribe them for short term or intermittent use.
  • Other prescription drugs such as Atopica, Cytopoint and Apoquel, which may be effective depending on the individual dog. They all come with their own pros and cons, so it’s best to consult your veterinarian for guidance.
  • Prescription corticosteroid eye drops to ease dog eye allergies. Rinsing the eyes with a sterile saline solution and wiping any discharge from the eyes regularly may also help.
  • Acupuncture, which can be an effective treatment, especially when used in conjunction with other therapies.
  • Antibiotics, if the irritation from an allergy creates a secondary bacterial or yeast infection.

Food-allergic dogs must never eat their triggering ingredients. Even flavored, chewable medication should be avoided. Do not offer your dog any table scraps or treats unless you are sure they are safe. Consider a product like Hill’s Prescription Diet Hypo-Treats, which have hydrolyzed protein, when you want to give your pup a tasty tidbit.

Here’s just one scenario that shows just how complex dealing with allergies can be. A friend of mine adopted a Bulldog mix named Mason who had chronic ear infections, inflamed skin, intense itchiness and hair loss. After an extensive diagnostic process that included an intradermal allergy test and a food trial, a veterinary dermatologist diagnosed Mason with both environmental allergies and food allergies and prescribed a hydrolyzed diet, hyposensitization shots, a medicated shampoo and Douxo S3 PYO Antiseptic Antifungal Dog & Cat Wipes to wipe him down in between baths. It’s something my friend has to stay on top of consistently, or else Mason’s symptoms flare up quickly.

Frequently Asked Questions About Dog Allergies

Allergies are a common problem without a simple diagnosis or universal treatment. What works for one dog may not work for another, and some experimenting is needed in almost every case. With all of this taken into consideration, it’s natural for pet parents to have questions. We’ve made a list of the most frequently asked questions here.


What is the cost of dog allergy testing?

A: Your dog allergy testing cost will depend on the type of test, your geographic location, your clinic and the specifics of your dog’s case. A good ballpark figure is $300 for intradermal skin testing or blood testing for allergies, but your veterinarian can give you a more personalized estimate of your total dog allergy testing cost. Avoid online DIY test kits, as these don’t provide accurate results.


Can you give a dog Benadryl for allergies?

A: As with any medication, it’s best to consult your veterinarian before giving Benadryl to your pet. Having said that, Benadryl is one of the few “human medications” largely considered safe for dogs. It’s not a powerful treatment for allergies, but it can provide relief in some mild cases or when used in combination with other therapies.


What are the most common dog allergies?

A: Flea allergy dermatitis is the most common dog allergy. It’s most prevalent in warmer months but can be a problem all year long, which is why year-round flea control is so important. Prevention is much easier than dealing with an infestation.

Commonly Prescribed Treatments


Apoquel Tablets for Dogs

Apoquel is an oral tablet that works differently than other allergy medications. It goes straight to the source to help relieve itch and inflammation at its core—addressing the underlying cause of irritation and soothing allergic reactions. It starts to relieve those unpleasant symptoms within 4 hours, and effectively controls itching within 24. (30 count)


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Simparica Trio Chewable Tablet for Dogs, 44.1-88 lbs, (Green Box)

Monthly Simparica Trio prevents heartworm disease, kills adult fleas and is indicated for the treatment and prevention of flea infestations, the treatment and control of tick infestations, and the treatment and control of roundworm and adult hookworm infections in dogs and puppies 8 weeks of age and older, and weighing 2.8 pounds or greater. (12 month supply)


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Revolution Plus Topical Solution for Cats, 5.6-11 lbs, (Orange Box)

6-in-1 broad spectrum monthly Topical Solution for Cats by Revolution Plus. Simply apply to help: kill fleas before they lay eggs, kill ticks for a full month, prevent heartworm disease and treat and control roundworms, hookworms and ear mites. Suitable for cats and kittens eight weeks of age or older, weighing between 5.6 and 11 pounds. (6 mo. supply)


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Atopica (Cyclosporine) Capsules for Dogs

Atopica is an oral solution prescribed to dogs who suffer from allergic dermatitis—a skin reaction caused by contact with an allergen. Very common in canines with allergies, and can cause their skin to become uncomfortably itchy, red and scaly. Targets root of the problem to help relieve itching. 100-mg (33.1-64 lbs)


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Atopica (Cyclosporine) Oral Solution for Cats, 100 mg/mL, 17-mL

Atopica is an oral solution prescribed to cats who suffer from allergic dermatitis—a skin reaction caused by contact with an allergen. Very common in felines with allergies and can cause their skin to become uncomfortably itchy, red and scaly. Targets the root of the problem to help relieve itching.


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Temaril-P Tablets for Dogs

Temaril-P is an oral medication prescribed to relieve irritation of the throat and coughing associated with allergic bronchitis. This easy-to-administer medication helps to relieve itching and inflammation due to allergies and other causes, working to prevent and suppress coughing. Comes in a tablet form, so you can feed it by mouth. (30 count)


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It’s tough to see our pets in distress and endlessly itchy due to allergies, but with patience and perseverance you can provide them with relief. Maintaining an open line of communication with your veterinarian will help you stay on top of your dog’s symptoms. Although managing dog allergies can be a painstaking process, the reward is well worth it for both you and your dog.

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By: Dr. Jennifer CoatesUpdated: