Dermatitis in dogs is a condition in which the skin becomes inflamed and irritated. This is a particularly frustrating condition in dogs because it can be caused by a number of different sources. Allergies to parasitic bites, certain types of foods, grasses, detergents, or plants are some of the leading causes of dermatitis in dogs; many other dogs suffering from dermatitis experience this condition from exposure or reaction to a fungus, or as a result of high temperatures and humidity.