When an allergic dog comes in contact with allergens, the dog's white blood cells create antibodies in response, and the outward signs of this response are usually itching and inflammation, leading to scratching and discomfort for the animal.

According to experts on the subject, allergic dogs develop allergen-specific IgE antibodies and IgG antibodies. IgE antibodies are involved in Type I hyper sensitivity reactions, the most common type of allergic reaction in the pet’s body. The actual immunology is quite complicated.

Simply put, IgE antibodies are formed upon exposure to environmental allergens such as mold, human dander, fleas, house dust mites, or pollen from grasses, weeds, and trees. These antibodies attach to a tissue cell called a mast cell and after continued exposure to the allergen, the allergen attaches to the IgE antibody mast cell combination. This binding causes the mast cell to disintegrate and releases chemicals contained within the cell and cell membrane. It is this release of chemicals that causes the allergic inflammation and reactions such as itching and scratching seen in allergic pets.

Some studies show that females are affected more than males. However, allergies can occur in any breed of dog and are occurring in more and more breeds of dogs as the environment and food gets increasingly contaminated.

Allergies usually occur within 1 to 3 years of a pet being exposed to continual environmental allergens. If you live in an area where there are few environmental allergens, your dog should consider itself lucky, since this will significantly improve the quality of your dog's life even if your dog has the genetic predisposition to allergies.