Contact dermatitis is a relatively rare skin disease that can occur when a dog or cat makes physical contact with a chemical or other irritating substance and has a negative reaction. There are two types of contact dermatitis -- allergic and irritant -- and while they are technically two different diseases, the symptoms and treatments are so similar that they are often grouped together. Read on to learn what you need to know about both types of contact dermatitis in dogs and cats.
Causes of Contact Dermatitis in Dogs and Cats
There are two types of contact dermatitis: allergic and irritant. In both cases, the pet must make direct physical contact with an irritating substance in order to suffer a reaction.
Allergic dermatitis occurs when a pet becomes hypersensitive to substances in their environment. Most allergic reactions require a period of repeated physical contact and skin sensitization, so even if your pet has come into contact with certain chemicals or substances in the past without issue, an allergy could develop, and it may seem like it came out of nowhere. However on average, skin sensitization can take anywhere from six months to two years to develop.
Common chemicals and substances that cause allergic contact dermatitis include: topical antibiotics, flea collars/flea powders, certain metals (such as nickel), grasses and pollens, soaps/shampoos, carpet deodorizers, insecticides, dyes, and materials such as rubber, wool, leather, and plastic.
Irritant contact dermatitis, on the other hand, does not require a period of sensitization. A reaction will occur the first time that your pet makes contact with an extremely irritating substance, and any other animal that comes into contact with the substance may have a skin reaction as well.
Common chemicals and substances that cause irritant contact dermatitis include: poison ivy sap, road salt (for melting ice), detergents, soaps, solvents, acids and alkalis, and petroleum byproducts (such as fertilizers, perfumes, and petroleum jelly).
Symptoms of Contact Dermatitis in Dogs and Cats
Contact dermatitis generally appears on areas of the body that are not well protected by hair, such as the feet, nose, lips, chin, stifles (“knees”), hocks (backs of “knees”), and underside of the body.
The primary symptom of both types of contact dermatitis is a skin rash characterized by itchy red bumps and inflammation. There may be weepy, blister-like lesions, hives, crusting, thickening, scaling, and hair loss. The pet will most likely scratch, bite, and lick the skin excessively, which may lead to a secondary bacterial infection.
In irritant contact dermatitis, you may also see ulcers.
Diagnosing Contact Dermatitis in Dogs and Cats
If you suspect that your pet is suffering from contact dermatitis, contact your veterinarian. Your pet’s medical history as well as current symptoms will usually be enough to diagnose the skin disease.
The tricky part is isolating the irritating substance. This is usually accomplished through either exclusion trials or a patch test. In an exclusion trial, the pet is placed in a neutral environment and potentially irritating substances are introduced one by one. In a patch test, the suspected allergen is rubbed or bandaged onto the pet’s skin. Then, the area of skin is monitored for several days.
Treatment for Contact Dermatitis in Dogs and Cats
There is no cure for contact dermatitis. The best way to treat and prevent the disease is to prevent exposure to the irritating substance. This may mean removing a plant from your garden, changing detergents, or keeping certain chemicals locked away.
In the short term, your veterinarian may prescribe topical or oral corticosteroids or antihistamines to control itching and reduce inflammation. Certain shampoos and sprays can also relieve itching and other symptoms. And if the skin is infected, your veterinarian may prescribe an oral or topical antibiotic.
In the long term, you may want to consider switching to a hypoallergenic pet shampoo, a hypoallergenic detergent to wash pet bedding, glass or stainless steel food and water bowls, and toys that do not contain rubber.
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