Any animal with fur can trigger an allergy, but the most common pet allergies are caused by our favorite little companions: cats and dogs.1 Both cats and dogs produce multiple allergens (or proteins that cause allergies).2 Homes with more than one cat have higher levels of cat allergens, and dog allergen levels increase if the dog primarily lives inside.2 While some dogs and cats are known to shed less than others, that does not necessarily mean that you can be less allergic to them. So-called hypoallergenic (meaning without allergies) dogs and cats may shed less than others, but no breed is truly hypoallergenic.1 Cat allergies may differ from dog allergies in terms of severity. Contact with a cat can trigger a severe asthma attack in up to 3 in 10 people with asthma.2 You may have also noticed that more people are allergic to cats than they are to dogs. Cat allergies are so common that there are twice as many people with cat allergies than people with dog allergies.2 Unfortunately, if you do have a dog or cat, it’s inevitable that their dander will end up everywhere. Pet dander collects very easily on our furniture, flooring and clothes. It’s also easily stirred into the air when you groom your pet, or dust or vacuum the house, which can mean that this allergy trigger can remain airborne for prolonged periods of time.2