Why Is My Dog So Itchy? Understanding Canine Allergies and Atopic Dermatitis
– by Justin Chan, DVM –
Common Causes of Itchy Skin in Dogs
Itchy skin. Incessant scratching and paw licking. Hair loss. Hot spots.
These issues have become some of the most common reasons our furry canine companions end up in the veterinary clinic—but what is causing them?
The answer often lies in canine allergies, also known as Canine Atopic Dermatitis (CAD), which are fundamentally different from the allergies that humans experience. Usually when we think of allergies, we think of itchy eyes, an itchy throat, watery eyes, and nonstop sneezing whenever pollen rears its ugly head in the spring.
However, our canine companions react to allergens differently. Instead of their sinuses becoming inflamed or their throat becoming itchy, dogs tend to develop skin and ear inflammation, which can eventually lead to infection if left untreated.
What Are Allergies in Dogs?
Ultimately, allergies are due to an overactive immune response (hypersensitivity) to substances in the environment such as fleas, foods, pollen, dander, or dust mites. The immune system treats these substances as dangerous invaders, leading to activation of the inflammatory pathway in an attempt to eliminate these perceived threats.
When the inflammatory pathway is activated, the skin becomes red, warm, and swollen, causing the characteristic itchiness and irritation associated with atopic dermatitis and allergies.
How Do Dog Allergies Cause Skin and Ear Infections?
Normally, a variety of microorganisms, including bacteria and fungi, coexist on the surface of the skin. These microorganisms typically keep each other in balance due to the limited nutrients available in healthy, non-inflamed skin.
However, when the skin becomes inflamed, the skin barrier is disrupted, allowing microorganisms to invade newly formed gaps where there is an abundance of nutrients available. These organisms can then rapidly reproduce, which further amplifies the inflammatory response as the body attempts to eliminate the infection.
Unfortunately, this process creates a vicious cycle. The increased inflammation provides even more nutrients for the microorganisms, while the body’s immune response remains ineffective at completely eliminating them. Over time, this can lead to recurring skin and ear infections.
Can Atopic Dermatitis Be Prevented?
Unfortunately, atopic dermatitis is an inherent immune condition that can develop in any companion animal. Certain breeds have been shown to be predisposed to this condition, including:
- West Highland White Terriers
- French Bulldogs
- Boxers
- Labrador Retrievers
Due to the prevalence of atopic dermatitis in these breeds, researchers suspect there may be a genetic component to the condition. However, there is currently no genetic test available to determine whether a dog will develop allergies.
Is Allergy Testing Available for Dogs?
Yes! Blood testing and intradermal allergy testing are available for dogs. The goal of these tests is to identify which allergens are triggering your pet’s flare-ups.
Once specific allergens have been identified, immunotherapy can be developed to gradually desensitize your pet to those allergens over time. Allergy testing is primarily used to identify and manage environmental allergies.
Food allergies, on the other hand, are best identified and managed through the use of novel protein or hydrolyzed protein diets.
Treatment Options for Dogs with Atopic Dermatitis
Treatment of atopic dermatitis can be divided into two distinct phases: treating any active infection and managing the underlying allergies.
Treating Active Skin and Ear Infections
If a patient presents with an active skin or ear infection, your veterinarian may perform a cytology to identify the specific organisms that are currently overgrown. Based on those findings, topical or systemic antibiotics and antifungal medications may be prescribed to address the infection.
Managing Underlying Allergies
Managing the underlying allergies is the key to preventing future flare-ups and helping your pet remain itch-free.
The goal of allergy medications is to modulate the immune system so the body no longer reacts excessively to harmless allergens while still maintaining protection against harmful microorganisms.
Oral medications such as prednisone, Apoquel, Zenrelia, and Numelve are available at many veterinary practices and may be prescribed based on your veterinarian’s discretion. An injectable medication called Cytopoint may also be recommended.
Food Trials for Dogs with Suspected Food Allergies
In some cases, a food trial may be recommended to determine whether food allergies are causing or contributing to your pet’s symptoms.
The gold standard for a food trial involves feeding either a novel protein diet (a protein your pet has never been exposed to before) or a hydrolyzed protein diet (a protein that has been broken down into components too small for the immune system to recognize).
If your pet’s allergies improve while on one of these diets, your veterinarian may consider gradually tapering medications to determine whether dietary management alone can adequately control the condition.
For a food trial to be successful, your pet must eat the prescribed diet exclusively. This means no treats, table scraps, flavored medications, or flavored chew toys, as these can inadvertently trigger flare-ups.
While strict dietary trials can be challenging, they can be incredibly rewarding if they help keep your pet comfortable and itch-free.
Helping Your Dog Find Relief from Allergies
Ultimately, atopic dermatitis can be a challenging condition for both pets and their owners. Fortunately, by working closely with your veterinarian, a customized treatment plan can be developed to help keep your pet as comfortable and itch-free as possible.
With allergy medications, our goal is typically to achieve an 80–90% reduction in clinical signs and flare-ups. If the initial treatment plan does not provide adequate control, your veterinarian may recommend adjusting medications or adding maintenance topical therapies to improve results.
Consultation with a veterinary dermatology specialist is always an option, and a referral can be facilitated at any point if additional expertise is needed.
While allergies may not be curable, they are highly manageable, allowing most dogs to live happy, comfortable lives with significantly reduced itching and fewer infections.
Call now or book your appointment online.
Your pet’s best health starts here.