By Linda Cole
A healthy immune system protects us from diseases. It’s a remarkable network of tissues, cells and organs all working in harmony to protect the body from infections, viruses and other microorganisms. However, sometimes the immune system reacts to something it believes is harmful to the body, overreacting in the way it responds. An estimated 15% of people are allergic to cats, dogs and other animals, but it’s our feline friends that cause more people to sniffle and sneeze than dogs. It’s estimated one in seven children between 6 and 19 years of age are allergic to cats. The reason has nothing to do with their hair though; the instigator is a protein found in cats.
Cat allergies in people are triggered by an overreaction of a super sensitive immune system to a protein (allergen) in cats called FEL d1. Scientists have isolated seven cat allergens that contribute to an allergy, but the FEL d1 protein is the most common reason why people are allergic to felines and it’s because of the size and shape of this specific molecule. It’s found primarily in a cat’s saliva, skin and urine.
The protein is spread on a cat’s fur as she grooms herself and can be deposited on your skin when she licks you. Someone who is super sensitive to cats can develop a rash on their chest, face or neck. When reacting to a perceived threat, the immune system releases a chemical, histamine, which causes congestion, runny nose, sneezing, itching and watery eyes. Symptoms can range from mild irritation or sneezing to life threatening flare ups in asthma sufferers. An allergic reaction to cats can happen immediately or appear four to eight hours after contact with a feline.
It’s possible to develop an allergy to certain foods, dust, mold, pollen or pet dander (particles of dried skin) at any time in your life. Just because you have never been allergic 
to pets in the past doesn’t mean you will never develop a cat or dog allergy. Cat allergies are twice as common as dog allergies, and people who are allergic to dogs can have a reaction to only some breeds.
People who are allergic to cats can have a reaction to felines regardless of the breed – even hairless breeds – and it is possible for some people to have an allergic reaction when around big cats. All felines produce FEL d1, but some individual cats produce less than others. You may be fine around one cat, but not around others. There are no cat breeds that are hypoallergenic. Male cats, especially ones that haven’t been neutered, produce more of the protein than females do.
It’s not cat hair that causes an allergic reaction, and even though dander can contain the FEL d1 protein, neither the coat nor dander cause someone to be allergic to cats. Allergens are present throughout the home and can remain active for several months. FEL d1 is around a tenth the size of dust allergens and drifts around in the air. It’s extremely light, and these microscopic allergens can float for hours and easily be inhaled into the lungs. Dog allergens don’t float around in the same way or as long as cat protein does. You can have an allergy to cats and not be bothered at all by dogs.
FEL d1 is also extremely sticky and can adhere to your skin, walls, clothing, bedding and other porous surfaces. It’s possible to carry the allergens on your shoes and clothes to places where cats have never been, like your pet-free friend’s home, the doctor’s office, your work place or a restaurant. The protein has even been found in the Arctic. Pet dander can be found in homes on walls, ceilings, fixtures, furniture, carpet, curtains and other places up to two years after a cat is no longer around.
Brushing or combing your cat daily can help reduce the amount of allergens in th
e air. Weekly baths may help as long as your cat’s skin doesn’t become dry and flaky. Changing your pet’s diet to a premium quality food containing Omega-3 fatty acids can help keep their skin healthy and supple. Shaving a cat will not help an allergy sufferer.
Last year, researchers from the University of Cambridge discovered that when cat dander comes into contact with a bacterial toxin – lipopolysaccharide or LPS – commonly found in the environment, it can trigger an allergic reaction to cats. They were also able to pinpoint which part of the immune system recognizes it: a receptor called TLR4. This research may bring about new treatments for people who deal with cat allergies as well as dog and dust mite allergies.
Top photo by Austin Kirk/Flickr
Bottom photo by A. Davey/Flickr
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