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Key takeaways

Contact dermatitis refers to inflammation of the skin in response to an allergen or irritant making physical contact with a dog’s skin cells.

  • Contact dermatitis can occur due to allergies or irritating substances
  • The most common contact allergen in dogs is flea saliva
  • Other common allergens include pollen, dander, dust mites and mold spores
  • Irritating substances that can cause contact dermatitis include shampoos, cleaning chemicals, herbicides, etc.
  • Contact dermatitis requires prompt veterinary attention
  • Symptoms include reddened, swollen and crusty skin or raised blister-like bumps
  • Diagnosis requires ruling out other causes of skin irritation and “patch tests” to test suspected irritants or allergens
  • Treatment involves removing suspected allergens or irritants from the environment
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A closer look: Contact Dermatitis in Dogs

Contact dermatitis is an allergic reaction which occurs when the immune system overreacts to a particular substance that is not otherwise irritating. Dogs with other allergic conditions are predisposed to allergic contact dermatitis. Contact dermatitis can also occur from touching irritating substances such as shampoos, cleaning chemicals, or certain textiles.

In some cases, contact allergies are extremely itchy and owners may notice hair loss in the itchy area.

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Risk factors

Contact dermatitis is uncommon in dogs, with the exception of Flea Allergy Dermatitis (FAD), which is the most common allergy in dogs.

Although it is a life-long condition, contact dermatitis has a good prognosis with appropriate management. Contact dermatitis is often severely itchy, but is not a life-threatening emergency.

Untreated contact allergies often become infected and painful, leading to skin lesions commonly referred to as hot spots. Hot spots, in turn, can become infected.

Symptoms of skin infections include

  • Weeping, open sores
  • Pus or blood oozing from the skin
  • Bad odor

Possible causes

oth allergens and irritants cause contact dermatitis. Irritants are chemicals, objects, medications, or plants that cause direct damage to the skin. Irritants generally affect every pet in the household. Examples include, but are not limited to:

  • Cedar chips
  • Textiles
  • Plastics
  • Metal
  • Fertilizers
  • Cleaning chemicals
  • Carpet or litter deodorizers
  • Soaps and shampoos
  • Insecticides
  • Herbicides
  • Topical medications

Unlike irritants, allergens activate the immune system to produce skin inflammation. Allergies develop over time, following multiple exposures.

Fleas are the most common cause of contact allergies in dogs. This subtype of contact dermatitis is called flea allergy dermatitis.

Other less-common contact allergens include:

  • Pollens
  • Dust mites
  • Mold spores
  • Animal or human dander
  • Insects
  • Environmental yeasts

Main symptoms

Contact dermatitis primarily occurs on the parts of a dog’s body that have less hair, as these areas have less protection to prevent the allergen or irritant from accessing the skin.

Testing and diagnosis

Identifying the cause of contact dermatitis often requires multiple steps. A review of the dog’s activities, lifestyle, and other factors help to identify potential triggers of the skin reaction.

As with other types of allergies, multiple diagnostics are usually performed to rule out other causes of the inflammation. These tests include:

  • Skin scraping
  • Fungal culture
  • Skin or ear swab

Contact dermatitis is suspected when other causes of skin inflammation are ruled out. The diagnosis is confirmed with a withdrawal test. The suspected irritant or allergen is removed from the dog’s presence. If symptoms resolve, and return upon re-exposure to that irritant or allergen, then the diagnosis is confirmed.

If there are many suspected allergens or irritants based on the dog’s history, the veterinarian uses patch tests to trial several possible items. In this test, the hair on an area of the body is clipped, and samples of suspected irritants or allergens are applied to the skin and bandaged in place. Samples that produce symptoms are confirmed as contact dermatitis-causing agents in that dog.

Steps to Recovery

Contact dermatitis is a life-long condition, but symptoms are expected to resolve as long as the irritant or allergen is removed. Treatment for contact dermatitis primarily involves eliminating the allergen or irritant through environmental changes. Bathing the dog routinely helps remove allergens and irritants from the skin. If removing the allergen or irritant is impossible, using a physical barrier such as socks or a shirt to separate the dog from the allergen or irritant helps reduce symptoms. Anti Inflammatory medications may be recommended when symptoms are present. Secondary skin infections are treated with antimicrobial medications as required.


As with any type of allergic reaction, the cause is unknown. Genetic predisposition may play a factor. Once contact dermatitis is diagnosed, recurring symptoms are prevented by removing the trigger from having contact with the dog.

Is Contact Dermatitis in Dogs common?

Contact dermatitis is uncommon in dogs. Allergic contact dermatitis is more common in dog breeds with an existing predisposition to allergies.

Typical Treatment

Contact dermatitis is generally treated by:

  • Preventing/limiting exposure to the trigger
  • Soothing shampoos
  • Treatment of secondary infections
  • Anti-inflammatories

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