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Dog Allergies: Signs, Symptoms, Diagnosis & Treatment Of Allergies In Dogs

Does your dog have allergies? Is your dog scratching with signs of rashes? See what type of allergy your dog has & how to treat it.

Aly Walansky

Updated December 14, 2022 • Published January 15, 2021

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Dog Allergies: Signs, Symptoms, Diagnosis & Treatment Of Allergies In Dogs

It’s allergy season for many of us. We wake up often with congested sinuses, stuffy noses, tickles in our throats, or watery eyes. In the current pandemic climate, it causes us stress. And dogs aren't immune to that; in fact, dog allergies are common enough. The types of allergies dogs get, and their reactions, may be somewhat different than us - but it can be just as stressful and confusing. That’s for them, and for us! Let's dig a little more deeply into the types of allergies dogs can get — and how to diagnose and treat them.

The different types of dog allergies

Flea Allergies

Flea or insect allergy is the most common allergy in dogs — your pet reacts to the flea's saliva. But there are many others to think about as well.

Flea allergies are by far the most common type of allergy that we see. “Keeping your pet on year-round broad-spectrum flea control preventatives is definitely recommended,” says Sara Ochoa, DVM, a small animal and exotic veterinarian in Texas and a veterinary consultant for doglab.com. Fleas or other parasites could be on the skin of the dog, leading to itching and scratching and biting.

Read More: Does Your Dog Have Parasites?

Environmental allergies

The seasonal type is the second most common allergen. These are “environmental allergens, such as pollens, molds, and spores,” says Dr. Ochoa. Much like an upper respiratory allergy or a skin allergy in humans, it's caused by something in our environment. “Atopy is an allergy to airborne pollen, molds, dust particles, and other irritants,” explains Dr. Michelle Burch, DVM at Safe Hounds Pet Insurance. This allergy is similar to hay fever in people but will cause skin irritation instead of sneezing and itchy eyes.

Food allergies

Food allergies may be the itchiest of the allergens, but also the rarest in dogs. “The most common ingredients dogs are allergic to are beef (95%), dairy (55%), wheat (42%), and chicken (24%),” says Dr. Burch. It's important to keep in mind that although “food allergies can cause some of the allergy problems that we see but, it's probably in less than 5% of the cases,” says Dr. Ochoa.

Read More: Does Your Dog Have Food Allergies?

The signs your dog has allergies

If your dog has allergies, they can show symptoms similar to humans, such as watery eyes, nasal discharge, sneezing, respiratory congestion and itching. “Chronic ear infections, shaking of the head, diarrhea, vomiting, licking of the paws, and loss of fur are also some signs to look out for,” says Sakura Davis, veterinary consultant and veterinary technician. Other signs your dog has allergies include:


A typical sign your dog is allergic to something is when their skin has a reaction, becomes red and irritated, and sometimes form a mild rash. “Though skin irritation is the most common sign, it is also the most difficult to pinpoint where the allergen came from, because it could come from anywhere,” explains Dr. Ochoa. A skin reaction could mean it was something they touched, but also could be something they ate or even something your pet inhaled.

Hair loss

A more severe skin reaction is hair loss. “Often hair loss can be associated with low-quality food, fleas, or parasites like Demodex, but it can be a sign of much more severe disease as well,” says Dr. Ochoa, who explains thyroid disease is common among dogs and cats and can make your pet very sick.

Tummy issues

If your dog has a food allergy, GI issues are usually the first signs you may notice. “If your dog has fur loss on the tail or near their behind and seems to be extremely itchy, this is usually related to infestation of fleas and flea bite allergy,” notes Davis. An environmental allergy is usually diagnosed due to inflamed skin (caused by constant itching and licking), watery eyes, and respiratory congestion.

Read More: Does Your Dog Have An Upset Stomach?

Itching and scratching

The most common sign of allergy in dogs is itching of the skin. “The location of itching can help clue owners on the type of allergen,” says Dr. Burch, who explained flea allergy itching starts at the tail base, which results in fur loss, redness, and scabs. The reaction will then continue along the back and down the sides.


Another potential indicator of allergies is hyperactivity or hypersensitivity. “Whether this is excessive licking of the body, barking that is not tied to any clear cause or trigger, or a new inability to settle that might show up as pacing or restlessness,” says Elisha McCallum of SpiritDog Training, an online dog training resource. Keep an eye on this kind of behaviour change as it can indicate discomfort in a pet.

Read More: What To Know About Your Dog's Zoomies

Appetite changes

One more thing that may be an indication of a food allergy in particular is your dog refusing food or treats they normally enjoy. Or, alternatively, “all of sudden your pet is much more food driven than they normally are, stealing food or begging for food when they did not do so previously,” says McCallum.

How to treat your dog's allergies

Diagnosis and treatment of allergies in dogs can be time-consuming, expensive, and frustrating, but patience is vital.

How to treat flea allergies

“I recommend all dogs, especially dogs prone to allergic flares, take a monthly flea preventative,” says Dr. Burch. Additionally, Dr. Burch recommends working with your veterinarian for workup and treatment of allergies. “I treat all allergy cases in dogs with an initial examination for fleas, secondary bacterial infection, mites, and fungal infection,” says Dr. Burch. Once these underlying causes have been ruled out, and dependent on clinical signs, more advanced testing is performed.

How to treat environmental allergies

Dr. Burch recommends that dogs with suspected environmental allergies have an intradermal skin test to determine what allergens they react to specifically. “A veterinary dermatologist typically performs an intradermal skin test,” says Dr. Burch. You may also have a serum allergy test performed on your pet’s blood, but this may miss some of the reactive allergens.

After determining the airborne allergies your pet reacts to, specific immunotherapy shots will be created. “Immunotherapy shots create a hyposensitization of your pet’s immune system to the allergen,” explains Dr. Burch. The shots will require six to 12 months to begin working, and 25% of dogs will not respond.

How to treat food allergies

Diagnosing a food allergy is accomplished with a food trial. “Your dog is started on a prescription diet with limited ingredients or the hydrolyzed proteins in the diet to prevent an immune response,” says Dr. Burch. These diets are fed for eight to 12 weeks to determine a response of improvement or not.

If improvements are seen, your dog can continue on the prescription diet lifelong, or you can slowly add back ingredients to see if your pet has an allergic reaction. “Each ingredient is fed for four to eight weeks before adding in a new one,” says Dr. Burch, who explains if there is a reaction, this ingredient must be removed from the diet, and a washout period of eight to 12 weeks must occur.

When to talk to a vet about dog allergies

Along with diagnosing the underlying cause and treatment, Dr. Burch cautions your dog will need supportive care to stop the itch, prevent the irritation, and treat any secondary bacterial infection. Your veterinarian will be able to prescribe the best medications needed for your dog, including medicated shampoos and wipes.

As with humans, once you identify the allergy, you can manage and treat it. It’s all about being watchful and observant and seeing how your dog responds and any health/behavior changes. Isn’t that all part of dog parenting anyway?

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