Irritant
contact dermatitis is caused by the direct effect of a chemical or irritant on
the skin.
It occurs in areas where the skin is not well protected by hair, such as the
feet, chin, nose, hocks, stifles, and the undersurface of the body, including
the scrotum. Irritant contact dermatitis can occur after a single exposure or
repeated exposure.
Irritant
contact dermatitis produces itchy red bumps and inflammation of the skin. You
may notice moist, weepy spots, blisters, and crusts. The skin becomes rough and
scaly and hair is lost. Excessive scratching damages the skin and sets the
stage for secondary pyoderma.
Chemicals
that can cause irritant dermatitis include acids and alkalis, detergents,
solvents, soaps, and petroleum byproducts.
Less
commonly, the skin becomes sensitized to a certain chemical and a delayed type
of hypersensitivity reaction develops. This is dermatitis. This rash is
indistinguishable from that of irritant contact dermatitis, but appears after
repeated exposure and often spreads beyond the site of contact.
Allergic
contact dermatitis can be caused by chemicals found in soaps, flea collars,
shampoos, wool and synthetic fibers, leather, plastic and rubber dishes,
grasses and pollens, insecticides, petrolatum, paint, carpet dyes, and rubber
and wood preservatives. Chemicals used to clean your carpet are a frequent
source of irritation. Neomycin, found in many topical medications, can produce
allergic contact dermatitis, as can other drugs and medications.
Plastic and
rubber food dish dermatitis affects the nose and lips.
Flea collar
dermatitis is an allergic contact dermatitis. The signs include itching,
redness, hair loss,
and the development of excoriations, scabs, and crusts beneath the collar. It
can be prevented to some degree by airing the collar for 24 hours and applying
the collar loosely. The flea collar should fit so that you can get at least two
fingers beneath the ring. However, if your dog develops flea collar
dermatitis, the best course of action is not to use a flea collar.
Treatment:
Consider the area of involvement and identify the chemical or skin allergen causing
the problem. Prevent further exposure. Treat infected skin with a topical
antibiotic ointment such as triple antibiotic. Topical and oral corticosteroids
prescribed by your veterinarian can relieve itching and inflammation.
