Does your nose stuff up or run when you're near a cat or dog? If so, you may have cat or dog allergies. The protein found in the saliva, dead skin cells (called dander), urine, and feces of furry animals is one of the most powerful indoor allergy triggers. Pets are second only to dust mites when it comes to causing perennial nasal allergies. More than 1 out of every 7 people has a pet allergy.

Cat Allergies

Cats are the biggest offenders when it comes to pet allergies. Oil glands in a cat's skin secrete proteins that are shed in dander and can cause cat allergy symptoms. In addition, when cats groom themselves, the allergy-producing proteins in their saliva coat their fur. When these tiny protein particles dry, they can easily become airborne. In the air, they find their way into sensitive noses, causing allergic reactions. Even cat urine contains these proteins. The proteins can last indoors and aggravate allergies for many months — long after the cat is around. Petting an animal is not necessary to produce an allergic reaction.

Dog Allergies

Dogs produce allergy-triggering proteins in their dander, hair, urine, feces, saliva, and blood. Some people believe that short-haired breeds, such as Chihuahuas, are less apt to cause allergy symptoms. But that's not true. How "allergic" a particular dog is depends more on how many skin cells are shed rather than the length of its hair.

Dogs and cats are not the only animals that trigger allergic reactions. Animals such as guinea pigs, hamsters, rabbits, gerbils, mice, rats, and other furry creatures can produce allergies in sensitive people. Even horses are known to cause symptoms in some people, especially those who spend time on farms, in stables, or at racetracks. Some people are so sensitive to horse proteins that furniture and mattresses made of horsehair are triggers.

People with allergies to birds usually find that anything made from feathers, such as goose down, can bring on allergy symptoms. These include pillows, cushions, or quilts.

How Pet Allergies Develop

Pet allergies can take up to 2 years or more to develop. It's common for researchers and others who are repeatedly exposed to furry laboratory animals to develop allergies. Unfortunately, once a person is sensitized, the symptoms of allergic reaction can last for up to 6 months or longer after the exposure ends. Animal allergens can also stay in the air and on furniture and carpeting for months after the pet is out of the house or the rat out of the lab. Some people are so allergic to cats and dogs that they experience allergy symptoms in schools and other public places from pet dander brought in on other people's clothing.