Staph bacteria that are normally present in the environment can produce an allergic response in some dogs. In animals with poor immune systems, the bacteria can invade the deeper layers of the skin and cause an infection called pyoderma.
Contact allergies are not commonly seen in pets. This form of allergy is a local reaction to some type of chemical.
Inhalant allergies, or atopy, are the most common kind of allergy seen in pets. Allergic reactions may be from tree pollen, grass pollen, weed pollen, mold spores, and house dust mites.
Food allergies typically take a long time to develop and can display themselves as skin problems or digestive issues.