Itchy and Scratchy

Does your dog or cat suffer from allergies? If your pet seems to be scratching a never-ending itch, he may be allergic to some of the same things you are: grasses, pollen, molds, the chemicals on certain fabrics or carpets, or even other pets. It's not unusual, for instance, for dogs to be allergic to cats. Theoretically, cats can be allergic to dogs, although it's not something that's commonly tested for, says veterinary dermatologist Kim Boyanowski of Peninsula Animal Dermatology in Redwood City, California. These types of allergies are known as atopic or inhalant, meaning they're absorbed through the skin or inhaled through the respiratory tract.

Pets can also have food allergies, but they're less common than inhalant allergies, Dr. Boyanowski says. For instance, only about 10 percent of allergic dogs exhibit true food allergies.

Unlike people, it's rare for cats and dogs to manifest allergies by sniffling, sneezing or coughing. A coughing cat, however, may have allergy-related asthma.

Allergies can be genetic, but whether a pet develops allergies depends on the convergence of three events: genetic predisposition, exposure to an allergen, and a reaction to that allergen. "If they are not genetically predisposed or they don't have an exposure or haven't triggered a reaction, they could theoretically on a blood test or skin test react as an allergic patient but not be displaying symptoms," Dr. Boyanowski says.