Clinically known as atopy, inhalant allergy is a hypersensitivity to environmental allergens manifested through irritation of the skin and ears. Atopy occurs in 10 to 15 percent of the dog population and tends first to occur when the canine is between one to two years old. Feline atopy can occur at any age. It is not uncommon for animals to have atopy in conjunction with other allergies such as food hypersensitivity and flea allergy dermatitis.
Patchy hair loss including bacterial demodex, or ringworm infection, or hormonal diseases such as hypothyroidism and Cushing's disease. These diseases should be ruled out by appropriate testing. Skin biopsy of affected areas shows dysplastic (abnormally shaped) hair follicles which are filled with keratin.
Difficult and painful defecation, perianal licking and chewing, foul smelling perianal discharge, low tail carriage, weight loss and lethargy.