Just like humans, dogs, cats and horses can be allergic. The immunological mechanisms underlying allergy in dogs, cats and horses are essentially the same as in humans. Allergy is a condition of hypersensitivity to substances which are common and harmless to most animals. The hypersensitivity is caused by a dysfunction in the pet’s immune system. The substances that cause allergy – allergens – include pollens, dust mites, molds, dander, insects, fibers and foods.

Exposure to the allergens, by physical contact, inhalation or ingestion, causes the body’s immune system to over-react and produce antibodies to fight off the invading allergens. The over-reaction generates an inflammatory response in the skin and subsequently cause itching, scratching and redness (atopic dermatitis). Respiratory symptoms (allergic rhinitis, asthma), gastrointestinal symptoms (vomiting, diarrhea, gastritis) and ocular symptoms (conjunctivitis) may also appear.