There are eight significant cat allergens, and most people are allergic to more than one cat allergen (just not as severe). The majority of cat allergies are reactions to a small secretoglobin protein called Fel d1.
Severe allergies to horses, rabbits, or dogs, or food allergies to pork, beef, or egg are always a concern in placing Siberian kittens, as many folks with these allergies react to to all Siberians.
We can safely place kittens in about 40% of these homes. The remainder may be unable to safely have a furry pet. Because of this risk, we start with fur tests, and then spending time with a tested low-allergen Siberian.
Pretend a PaperMate Pencil and PaperMate Pen are two different allergens in the same class. Your immune system can attach at different epitopes or “latch-points.” These points might include the writing tip, barrel, shirt clip, and eraser. If your immune system latches onto the shirt clip of the Pencil, you will also react to the Pen, because the shirt clips are the same. If my immune system latches to the writing tip of the Pencil, I won’t react to the Pen – as the latch point is different p.
Allergens are named by species and order of discovery, so Cat Allergen #1 = Feline domesticus #1 = Fel d1. Looking the three commonest cat allergens we can see why these “cross reactions” occur.
Fel d 1 ~ Cat uteroglobin: does not share epitopes with most domestic animals.
Fel d 2 ~ Cat serum albumin: shares epitopes with Horse, Pork meat & Beef.
Fel d 4 ~ Cat lipocalin: shares epitopes with Horse, Rabbits, Boar, Mouse, Cow
Fel d 7 ~ Cat lipocalin: shares low similarity epitopes with Dog, Cow
Serum Albumin (Fel d2)
Serum albumin accounts for about 30% of cat cross-reactions between cats, dogs, pork meat, or egg white, and reactions vary from mild to severe. Allergies from albumin can cause similar symptoms as allergies to Fel d1.
Albumin is a protein made by all animals. It holds fluids in the bloodstream and carries vitamins and enzymes through the body. Cat albumin has all the same functions as albumin in other mammals, but the structure of albumin is slightly different in each species.
There are 6 different epitopes (latch points) on albumin. Our immune system can cross-react to albumins from different animals, as different species will have some identical epitopes and some that are slightly different. Our immune system is highly adaptable, so each person will react to allergens in a different manner.
Lipocalin (Fel d4)
Lipocalin is a respiratory and dermal allergen, causing both asthma and eczema. Roughly 25% of people with horse/rabbit allergies react to feline lipocalin. Studies show that intact male mice produce 500 to 1000 times more lipocalin than female mice, so neutering cats might reduce lipocalin allergies.
Horses are a significant source of animal allergens. Up to half of folks with prolonged contact with horses develop reactions. Anaphylaxis from exposure to horse albumin or lipocalin can occur in children without warning, though minor symptoms (asthma, itching, eczema) are usually present first. Carrying Children’s Chewable Benadryl when allergic children visit horses will reduce the risk of dangerous or fatal reactions.
.More detailed information about cat allergies: