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What Are Dogs Allergic To? Common Allergens

Beagle sneezing in field of flowers
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Just like humans, dogs can be allergic to a wide variety of things, from pollen and dust to different foods. An allergy occurs when the body overreacts to certain substances called allergens, releasing histamine in an attempt to destroy the perceived invader. 

Allergens, which are usually proteins, can be found in plants, animals, insects, and even foods. Dogs can also experience allergic reactions to chemicals, materials, and medications.

Read on to explore common dog allergies, allergy symptoms to look out for, and how to help your dog.

Signs of Allergies in Dogs

Dog licking paws

In humans, allergies are commonly associated with sneezing, runny nose, and watery eyes. Although some allergic dogs do show these symptoms, allergies in dogs more commonly manifest as inflamed, itchy skin. The inflamed skin sometimes leads to skin or ear infections. Other dogs might have gastrointestinal signs, such as vomiting or diarrhea.

“Allergy symptoms in dogs can be similar to those of other medical conditions,” said Dr. Alejandro Caos, a veterinarian with at-home veterinary service The Vets. “A veterinarian can perform diagnostic tests to determine if the symptoms are indeed caused by allergies or if there is another underlying medical issue.”

Depending on the type of allergy and the individual dog, you might see:

  • Red, itchy skin
  • Rash
  • Skin infections
  • Hives
  • Poor coat
  • Excessive self-licking, especially of the paws
  • Sneezing
  • Watery eyes
  • Itchy ears
  • Ear infections
  • Facial swelling
  • Vomiting 
  • Diarrhea
  • Scooting on the ground

What Are Dogs Allergic To? Common Allergens

Beagle dog scratching

Knowing what is causing your dog’s allergies is the key to helping them find relief. Dogs might be allergic to just one allergen or might be affected by multiple allergens throughout the year.

“It’s super important for pet owners to work with their veterinarian to determine the cause of their dog’s allergies before attempting to treat the symptoms,” said Dr. Lindsay Butzer of Clint Moore Animal Hospital in Boca Raton, Florida. “Allergies can have many different triggers, and treating the symptoms without addressing the root cause won’t provide long-term relief for your furry friend.”

According to Dr. Caos, allergies in dogs can be broken down into five general categories: 

  • Flea allergies (flea allergy dermatitis, caused by flea bites)
  • Environmental allergies (e.g., pollens, mold, dust, and mites)
  • Food allergies
  • Contact allergies (any substance that contacts the skin, including plants, fabrics, and chemicals)
  • Insect stings (e.g., bees, wasps)

What Plants Are Dogs Allergic To?

In addition to dust, mold and mites, environmental allergies in dogs can be caused by almost any plant pollen spread by the wind. Common culprits include grass pollens, weed pollens, tree pollens, and flower pollens. Any pollen can be a potential allergen. 

What Foods Are Dogs Allergic To?

Dogs can have adverse reactions to foods, whether true food allergies or food intolerances. Dogs can be allergic to any food ingredient, but according to one study, the most common food allergens in dogs are: 

  • Beef
  • Dairy products 
  • Chicken 
  • Wheat

What Other Things Are Dogs Allergic To?

Contact allergies, caused by substances that come in contact with the dog’s skin, are less common than flea allergies, environmental allergies, and food allergies. Dogs can suffer from contact allergies to almost any substance, but common offenders include:

  • Cleaning products
  • Laundry detergent
  • Carpet fibers
  • Plants
  • Ingredients in topical parasiticides or flea collars
  • Topical medications and shampoos
  • Metals

How to Help Your Dog With Allergies

ova Scotia Duck Tolling Retriever taking a bath at home

To know how to best treat and prevent allergies, your vet first needs to identify what your dog is allergic to. In addition to conducting a comprehensive physical exam, your vet will ask you questions about your dog’s lifestyle and when the allergies seem to be the worst. If signs of a flea infestation are seen, your vet will recommend starting your dog on an oral or topical flea preventive.

Allergy testing can be helpful to pinpoint environmental allergens. “Intradermal skin testing involves injecting small amounts of allergens under the skin to identify which allergens cause an allergic reaction in the dog,” Dr. Caos says. 

Food allergies are usually diagnosed using an elimination diet trial. Your vet will instruct you to feed your dog a special minimal-ingredient prescription diet that contains a single protein and a single carbohydrate source for about 8 to 12 weeks. During the trial, the dog cannot eat any other foods, including “people foods,” treats, or oral medications (including preventatives) that have added flavors. Speak with your veterinarian before discontinuiing any medications.

If the dog’s symptoms improve during the elimination diet trial, a food allergy is suspected. To identify the specific food or foods that the dog is allergic to, other ingredients are re-added back to the dog’s diet, one at a time. If the dog’s allergy symptoms return after the reintroduction of a certain ingredient, the allergy is confirmed. 

Once your vet has diagnosed allergies in your dog, they might prescribe or recommend certain medications. “There are several prescription medications available to treat allergies in dogs,” Dr. Butzer says. “These may include corticosteroids, antihistamines, and immunosuppressive drugs like cyclosporine. Your veterinarian will recommend the best treatment based on your dog’s specific needs and the severity of their allergies.”

Apoquel is a commonly prescribed oral medicine for allergic itch in dogs that provides fast, effective relief.

Apoquel medication bottle

Allergen-specific immunotherapy (ASIT, sometimes called allergy shots) can help improve a dog’s tolerance to allergens, in turn reducing allergy symptoms. 

You can also help your dog by removing allergens from their environment through frequent cleaning and vacuuming, and washing your dog’s bedding regularly. Bathing your dog with a moisturizing oatmeal shampoo can help soothe itchy skin and remove pollen, dust, and other problematic substances from their fur. If the allergies are caused by food, avoiding the problem ingredients should resolve your dog’s allergies. Keep in mind that some dogs may have multiple types of allergies, so management may be more complex in these scenarios.

Allergies can be uncomfortable for dogs, and management of allergies in dogs is usually lifelong. Identifying what’s causing your dog’s allergies is the key to relieving their discomfort, but you can rest assured that veterinarians are skilled at diagnosing allergies. 

“Allergy testing is not always necessary to diagnose allergies in dogs, as other methods can be used,” Dr. Caos says. “A veterinarian will determine the most appropriate diagnostic approach based on the dog’s symptoms, medical history, and potential exposure to allergens.”