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dog allergy symptoms

8 Dog Allergy Symptoms

**If your dog is experiencing facial swelling, sudden hives or raised red welts on their skin, or difficulty breathing, please have a veterinarian evaluate your dog in person immediately, as this can be due to a potentially life-threatening allergic reaction.**


Is your dog licking, chewing, scratching, or shaking their head more often than usual? Does your dog suddenly have areas of thinning hair, excessive shedding, baldness, or spots of rust-colored staining to his fur? Is your dog constantly scooting his rear end on the floor and licking beneath his tail? These concerns are some of the most common your AskVet veterinarians hear from pet parents. Many times, these signs are the tip of the iceberg, and that iceberg is dog allergies!

Now, you may be asking, can dogs have allergies? The short answer is yes. Allergies and their related symptoms are frequently encountered in our furry friends. In this article, we’ll teach you what your AskVet veterinarians want you to know about pet allergy symptoms, and why your veterinarian may recommend multiple avenues of testing and various methods of treating dog allergies. 

In some cases, a dog’s allergy symptoms will consist of watery eyes and sneezing —but this is definitely the exception rather than the rule! In this article, we’ll focus on the most common manifestations of dog allergies and signs of allergies in dogs: how dogs express allergies through their skin. Itchiness, redness, inflammation, and infections are all skin conditions that are often caused by underlying allergies. 

Why Would My Dog’s Skin Become Itchy?

Picture your dog’s skin like a brick wall. In healthy skin, the brick wall is sealed tightly between the bricks with cement, and nothing can get through. Bacteria and yeast are on the surface of the “brick wall,” along with pollen, dust mites, grass residue, floor cleaners, and everything else your dog encounters in their daily life. However, nothing can get through the tough cement of the brick wall–which is actually the skin’s natural healthy barrier. 

In dogs with allergies, however, the “cement” between the bricks has gaps—imagine a brick wall that is poorly sealed, with holes in between the bricks! These microscopic gaps allow particles of pollen, dust, and other allergens to get through the outer defenses of your dog’s skin and cause trouble. Once under the surface of the skin, allergens cause your dog’s immune system to go into overdrive, leading to redness, itchiness, and sometimes swelling. 

When your dog feels itchy, what do they do? Well, if they can reach the spot by scratching, then, of course, they will! If it’s more convenient for your dog to lick, chew, or rub the body part that is itchy, you might see them do any or all of these, too. We commonly see dogs with allergies rub their face on the floor, chew their paws, and lick under their arms. Dogs have glands that are located just inside the rectum and open on the surface of the skin—so you might even see frequent “butt scooting” in allergic dogs, too. 

How to Treat Allergies in Dogs | AskVet

Areas of your dog’s itchy skin may develop red spots, pimples, brown/yellow crusts, or little bumps as a result of the skin allergy. Sometimes rashes like this indicate that an infection has also taken hold in your dog’s skin—from microbes getting in between the “gaps between the cement” of your dog’s skin, or due to their overgrowth on the skin surface. Bacteria and yeast will gladly multiply with help from the warmth and moisture of your dog’s natural licking, chewing, and scratching. All of that scratching and chewing opens up more holes in your dog’s skin barrier, allowing bacteria and yeast under the surface. Once under the skin, bacteria and yeast flourish, and cause even MORE itchiness, redness, and discomfort–and the cycle of misery continues.

If your dog has been licking, chewing, scratching, rubbing, or biting an itchy area, you might see hairs broken off (called “barbering”), or even bald patches. Rust-colored staining to the fur is also a common finding. Veterinarians sometimes feel like forensic scientists, since sometimes we can look at this staining and immediately know what areas are bothering your dog the most! The red color comes from a pigment in your dog’s saliva (called porphyrin) that changes color when it is in prolonged contact with the fur. Therefore, any area that has this red staining is undoubtedly being licked/chewed at by your dog—even if they are waiting until you aren’t around to see them! 

What About Ears?

Pet parents frequently reach out to us about their dog’s itchy and stinky ears. Your dog might be frequently shaking their head, holding their head to one side like their ear is painful, and/or frequently scratching at their ears. You might see red, brown, or even yellow goop inside your dog’s ears when you lift the ear flap. 

Many times these symptoms are due to ear infections, with or without the presence of other common dog allergies. Interestingly, allergies to certain food proteins, as well as environmental allergens, can actually cause repeated episodes of itchy, infected ears. 

Why would allergies, even a dog food allergy, cause an ear infection? It’s actually pretty simple! The lining of the ear canal is part of your dog’s skin—and just like skin covering the rest of your dog’s body, allergens, yeast, and bacteria, in addition to a damaged “brick wall” can cause inflammation and itchiness. The inside of your dog’s ear is warm, moist, and dark—which is the PERFECT environment for yeast and bacteria to thrive! Your family veterinarian can diagnose which organisms are causing an ear infection by taking a non-painful sample from the inside of the ear and looking at it under a microscope. 

What Can My Dog’s Itch Tell Me About His Allergies? 

Plenty! While allergy testing and/or a hypoallergenic food trial are the only ways to know with certainty what your dog might be allergic to, you can actually deduce a lot of information based on when and where your dog is the itchiest. 

For example, if your dog is frequently getting rashes on their belly, but never seems to have any problems on the top of their back, then your dog might be allergic to something their tummy is frequently in contact with. If your dog likes to lay in a certain patch of grass, or on a favorite blanket, then pollen or detergent residue may be an allergen to your dog.

If your dog is only itchy on the top of their rump and base of their tail—but your dog’s skin is calm and comfortable everywhere else–then your dog may be suffering from flea allergies. 

Itchy paws and repeated ear infections might make a food allergy more likely in your dog’s case, especially if these symptoms are present throughout the calendar year. After all, we typically feed our dogs the same thing year-round, so your dog would be constantly exposed to their allergy trigger.

Many dogs have long periods of the year without skin or ear problems, and instead seem to have problems “like clockwork” during certain seasons. In these dogs, environmental allergens (pollens, grasses) are more likely than a food allergy, since they tend to appear seasonally in your dog’s environment.

Just to add to the fun, some dogs have both a food AND environmental allergy—and in warm climates where plant life flourishes year-round, it can be even harder to detect a pattern to your dog’s itchiness! 

Talk to a Trusted Vet

Your AskVet veterinarian can give you tools for determining your own dog’s personal itch history, which can help your family veterinarian optimize your dog’s treatment. Reach out to AskVet any time if you have questions about your dog’s allergies, or if you want to better understand your veterinarian’s recommendations or allergy medication prescription. Allergies are a lifelong exercise in management, observation and patience, but working as a team with your AskVet Veterinarians and your family veterinarian can help your dog live a long happy life with comfortable skin!

Written by:

Allison Ward, DVM
Dr. Allison Ward grew up in the suburbs of Washington, D.C. and started working in veterinary hospitals when she was 14 years old. After graduating from veterinary school in 2011, she completed a small animal rotating internship in New Jersey, followed by a neurology/neurosurgery internship in Miami. After completing this advanced training, Dr. Ward then moved on to general small animal practice. Dr. Ward’s professional interests include feline medicine, neurology, and pain management. Her passion for educating pet owners carries over into her work with AskVet, and she loves being able to help pets and their parents at all times of the day (and night!). She currently resides in sunny south Florida with her two cats, Larry and George.


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