Many allergic owners obtain pets without thinking through the difficulties of living with them. And too often, they end up relinquishing pets, a decision that is difficult for the owner and can be life-threatening for the pet. Cats and dogs are allergenic (allergy-causing) to people who are allergic to animals. Cats tend to be more allergenic than dogs for allergic people, although some people are more sensitive to dogs than cats. Contrary to popular belief, there are no "non-allergenic" breeds of dogs or cats; even hairless breeds may be highly allergenic.
Dogs with soft, constantly-growing hair may be less irritating to some individuals, although this may be because they are bathed and groomed more frequently. One dog or cat of a particular breed may be more irritating to an individual allergy sufferer than another animal of that same breed.
The source of irritation to pet-allergic humans? Glands in the animal's skin secrete tiny allergy-triggering proteins, called allergens, that linger in the animal's fur but also float easily in the air. Allergens are present in the animal's saliva and urine, too, and may become airborne when saliva dries on the fur. The severity of reaction to these allergens varies from one person to the next, ranging from mild sniffling and sneezing to life-threatening asthma, and can be complicated by simultaneous allergies to other irritants in the environment.
Ask your allergist to specifically test for allergies to pet dander, rather than making an assumption. And understand that allergies are cumulative. Many allergy sufferers are sensitive to more than one allergen. So, if you're allergic to dust, insecticides, pollen, cigarette smoke, and cat dander, you'll need to reduce the overall allergen level in your environment by concentrating on all of the causes, not just the pet allergy. For example, you may need to step up measures to remove cat dander from your home and carefully avoid cigarette smoke during spring, when it is difficult to avoid exposure to pollen. Immunotherapy (allergy shots) can improve symptoms but cannot eliminate them entirely. They work by gradually desensitizing a person's immune system to the pet allergens. Allergy-causing proteins are injected under the person's skin, triggering the body to produce antibodies (protective proteins) which block the pet allergen from causing a reaction. Patients are usually given one dose per week for a few weeks to months (depending on the severity of the allergy) and then can often manage with one injection per month. Additional treatments for allergies to pets are symptomatic, including steroidal and antihistamine nose sprays and antihistamine pills for asthma, there are multiple medications, sprays, and inhalers available. It is important to find an allergist who understands your commitment to living with your pet. A combination of approaches—medical control of symptoms, good housecleaning methods, and immunotherapy—is most likely to succeed in allowing an allergic person to live with pets. If you do suffer from allergies, specifically from pets, and before you adopt, be sure to consider carefully whether you can live with the allergy before you bring a new pet home. Except in the case of children, who sometimes outgrow allergies, few allergy sufferers become accustomed to pets to whom they are allergic.