According to the Asthma and Allergy Foundation of America, 15–30 percent of people with allergies have an allergy to dogs, cats, or other animals, with cats being the most common cause. Something in the immune system reacts badly to proteins secreted by oil glands in an animal’s skin and found on flecks of shed skin, as well as those in animal urine or saliva, can cause allergic reactions for some people.
Symptoms are similar to those described for hay fever above. The allergy can take two or more years to develop and symptoms may not subside until months after ending contact with the animal. Direct contact with animals is not always necessary to trigger allergies. For example, it could be caused by a pet that used to live in the house, or remnants carried on the persons living with animals.
As a result, it may be obvious that animals are the cause of your allergy. Symptoms may last for a very long time after exposure, so the causal relationship to pets may not be immediately obvious. If your pet is causing allergies, keep it out of your bedroom, avoid carpets in your home (which retain pet hair & skin), ventilate your house thoroughly and have the animal washed the animal regularly. Thorough vacuuming may also help reduce the irritants in the house, especially if your cleaner specializes in removing pet hair and filters the air well.
If you suspect you have an animal allergy, but still want a pet, consider an animal with a shorter coat which tends not to shed as much. Research your pets before you decide. There are many benefits to having a pet, so think twice before abandoning the idea.