Contact dermatitis is an uncommon skin disease of dogs caused by contact with plants (especially plants of the wandering Jew family), medications, and various chemicals.
Contact dermatitis can be of two different types: allergic or irritant.
Irritant contact dermatitis is caused by the direct effect of a chemical or irritant on the skin such as salt on road and, sap poison ivy. 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.
Contact allergy is a delayed reaction with signs occurring 24 to 48 hours after contact with the offending substance. Typical signs of contact allergy include pruritus (itchiness) and a papular eruption (red bumps).
Difference between the two conditions is that allergic contact dermatitis only affects those animals with a hypersensitivity to the molecule. Irritant contact dermatitis would affect every dog that is exposed to the irritant.
Allergic dermatitis requires multiple exposures to the molecule before it develops. It rarely occurs in animals less than two years old. Irritant contact dermatitis often occurs in inquisitive young animals who get into things they should not.
Some breeds are predisposed to allergic dermatitis such as German Shepherds, French Poodles, Wire-haired Fox Terriers, Scottish Terriers, West Highland White Terriers and Golden Retrievers.
If the condition occurs at certain seasons, it indicates that the offending source is a plant or outdoor compound.
Symptoms associated with contact dermatitis are
Redness on the skin
Lesions or ulcers on the skin
Runny eyes and nose