Contact Dermatitis in Dogs

What Is Contact Dermatitis in Dogs?

Contact dermatitis in dogs is characterized by a skin reaction that occurs after prolonged contact with an irritant known as an allergen. These are typically protein molecules that trigger an immune response—including the production of antibodies—that leads to symptoms like itching, redness, crusting, and pustules on the skin.

This condition is relatively uncommon in dogs, primarily because of the protective barrier provided by their fur coat. As a result, most symptoms of contact dermatitis develop on the parts of the dog’s body that come into direct contact with potential irritants. These areas are usually sparsely haired and include:

• The muzzle

• Mouth

• Armpits

• A dog's pressure points (elbows, ankles)

• Belly

• Groin

• Scrotum

• Rear end

• Paws

Some of the most common substances that can trigger contact dermatitis in dogs are:

• Plants

• Detergents

• Mulch

• Rugs and carpet

• Fabrics

• Plastics

• Concrete

• Medications

• Chemicals

• Fertilizers

While localized skin irritation in dogs is not considered a medical emergency, it should still be examined by your veterinarian.

This is because symptoms have the potential to worsen, secondary infections may develop, and your dog may continue to experience a lot of discomfort due to persistent itching and scratching. 

Symptoms of Contact Dermatitis in Dogs

The symptoms of contact dermatitis will often come and go depending on the duration and timing of contact with the allergen. The following symptoms are most common:

• Red and inflamed skin

• Hair loss

• Hardened scales, flakes, and scabs

• Darkened skin

• Pustules or pimples

• Itching

Causes of Contact Dermatitis in Dogs

Contact dermatitis is a hypersensitivity reaction that leads to a localized immune response and inflammation when chemicals (such as allergens) encounter the exposed skin of a dog.

Prior sensitization is necessary for this reaction to occur, indicating that the immune system recognizes the allergen as a threat and produces antibodies to fight against it. This sensitization process usually takes about six months to two years to develop. Once it occurs, subsequent exposure to the same allergen will trigger an allergic reaction.

Contact dermatitis can affect dogs of any breed, gender, and age, provided that the dog is older than six months. However, dogs who already have allergies may experience more severe or frequent flare-ups. 

How Veterinarians Diagnose Contact Dermatitis in Dogs

Typically, the distribution of skin lesions on contact surfaces such as the face, paws, belly, and rear are often enough to raise suspicion that your dog has contact dermatitis.

However, though patch testing can be challenging to perform and yields variable responses in dogs, it is the preferred method for diagnosing contact dermatitis.

This process typically involves shaving the hair on your dog’s side, usually a couple of days beforehand, and applying the suspected allergen (such as plant material) directly to the skin for about two days. Any resulting response (with symptoms like those described above) is noted within a few days after the application.

Alternatively, avoidance of the suspected allergen (typically requiring about a week) followed by a “rechallenge” (putting the dog back in the environment or in contact with the allergen) can lead to a response, potentially allowing for a presumptive diagnosis of an allergy. 

Because dogs with other types of skin disease usually have similar symptoms, your veterinarian may recommend additional tests such as a skin impression, skin scraping, or fungal testing (including a Wood’s lamp examination, fungal culture, or fungal PCR) to check for evidence of bacterial and/or yeast infections, mites, or ringworm.

A biopsy—involving the surgical removal of a sample of your dog’s skin—may be needed to rule out more serious skin conditions like pemphigus or cancer.

In complex or persistent cases, a consultation with a veterinary dermatologist may be required.  

Treatment of Contact Dermatitis in Dogs

While easier said than done, the most effective treatment for contact dermatitis is the avoidance of the triggering substance.

Unfortunately, there is no single medication or vaccine that can completely prevent your dog from reacting to allergens, but there are several therapies that can help provide your dog a relatively pain-free and good quality of life.

In cases where secondary bacterial or yeast infections are present, treatment is required and typically involves antibiotic or antifungal medications. Often, medications such as cephalexin, Simplicef®, or Clavamox® are used alongside fluconazole or miconazole.

Alleviation of itching is accomplished through antihistamines, steroids, or newer medications like Apoquel® or Cytopoint®. 

Topical therapies—including ointments, shampoos, and conditioners containing antibacterial, antifungal, and/or steroidal properties—are often prescribed. Under the guidance of your veterinarian, bathe your dog. This can lessen your dog’s symptoms and make your pup more comfortable and less itchy. 

Some products with fatty acids that can help your pup’s skin and coat quality include:

• Vetoquinol® Triglyceride Omega

• Hypoallergenic dog shampoos, such as Douxo S3™ CALM

• Medicated dog shampoos

• Supplements, such as Zesty Paws® Wild Alaskan Salmon Oil for Dogs

These products may also help maintain your dog’s skin barrier and reduce inflammation. 

Additionally, specialized diets designed to strengthen the skin barrier, soothe, and nourish a dog’s skin, and support their immune system—such as Hill’s® Derm Defense™—could be helpful.

Consult with your veterinarian to determine the best topicals, supplements, and diet for your dog, considering their unique medical and nutritional needs.

Recovery and Management of Contact Dermatitis in Dogs

The prognosis for dogs suffering from contact dermatitis is often good if the offending allergen is identified and avoided. In some cases, dogs may need lifelong medication—such as pentoxifylline or cyclosporine—to reduce their sensitivity. 

Prevention of Contact Dermatitis in Dogs

While it’s not always possible to completely prevent contact dermatitis in dogs, there are steps you can take to minimize exposure and reduce the risk of recurrence of symptoms in your dog.

Avoiding contact with the allergen whenever possible is key, which may involve measures such as:

• Removing carpeted areas or rugs

• Removing plants and weeds

• Using HEPA filters

• Changing the type of water or food bowl

• Maintaining a strict flea control regimen 

Barrier methods like recovery collars or T-shirts—as well as more frequent bathing with or without leave-in shampoos and conditioners—may be helpful.

Preventing your dog from excessive licking and scratching is essential to avoid future infections. Additionally, monitoring pollen counts and having your dog examined by your vet at the first sign of itching can help manage and minimize the impact of contact dermatitis.

Contact dermatitis itself is not contagious to other dogs or people. However, due to the frequent use of antibiotics in affected dogs, there is an elevated risk of developing multi-resistant skin infections, and certain precautions should be taken:

• Use topical therapies as the first line of treatment.

• Perform skin cultures regularly.

• Immunocompromised individuals should take additional precautions and discuss their concerns with both their vet and physician.