Atopy, also known as atopic dermatitis, is a condition, thought to be inherited, in which your dog is predisposed to having allergic reactions to normally harmless substances such as grass, dust mites or even certain foods.

Your dog will be very very itchy. He will scratch, lick or chew at his skin which will can cause hair loss, red skin or thickened skin. If the condition progresses unchecked, your dog will likely develop bacterial or yeast infections in the impacted areas. 

Atopy appears to be an inherited disease. Most dogs develop atopy when they are young adults between the ages of 1 to 3 years.

Although any breed or mix can develop, certain breeds seem at greater risk. These breeds include Bulldogs, French Bulldogs,Golden Retrievers, Lhasa Apsos and Old English Sheepdogs.