If your eyes water, and you start to sneeze after playing with or just being near a furry animal like a cat or dog, you may have an animal allergy. Animal dander — a combination of skin, fur, and saliva—is extremely tiny and lightweight, so it can stay in the air for hours, which could cause symptoms long after the animal has left the room. And dander can land and stay on furniture, carpets, mattresses, upholstery, or your clothing, so people who have pets can unknowingly carry dander with them everywhere they go, including school or work.

An allergy to furry animals—cats and dogs in particular—is considered to be a risk factor for developing asthma and hay fever. Nearly 30% of people with asthma have been found to have had an asthma attack brought on by cats.

And despite what you may have heard, there are no truly hypoallergenic breeds of dogs or cats.