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Cats

There are an estimated six million Americans, or about 2% of the population of the United States, who are allergic to house cats (Felis domesticus). In the United Kingdom, where it is thought that every one in four houses contains a cat, a third of asthmatics, and up to 40% of asthmatic children, are believed to be sensitised to cat allergen. The rate is as high as 80% for asthmatic children who lived in a home with a cat throughout the first year of their life. When they come into contact with cat allergens they typically experience red, itchy eyes and an inflamed, runny nose. Cat allergen can also prompt asthma attacks in asthmatics.

Cats are a much more prominent allergy trigger than dogs. The most important cat allergen is called Fel d1. Cat allergen is a digestive protein contained in saliva produced by the cat's sebaceous glands. When the cat preens itself, the protein is transferred to the fur of the cat and becomes shed in its dander. It is not the cat fur itself that causes an allergic reaction but the protein that is attached to it, so there is no real link between the length of the a cat's hair and the amount of allergen produced. All cats will produce allergenic dander in the form of skin flakes.

Once these proteins dry and evaporate off the cat, these microscopic allergen particles become airborne and can be inhaled into the lungs or nose. These inhaled allergens are more likely to provoke a rapid onset of allergy symptoms in sufferers. Cat allergen is about one-tenth the size of dust mite allergen and can stay airborne for a considerable length of time. The allergen is quite sticky and can be easily carried to other locations on people's clothing. This explains why cat allergy has been found in areas where no cat has been present, including schools, offices and public buildings.

Areas where a cat is present are more likely to aggravate allergies, with studies showing that an increase in the levels of cat allergens detected the air occurred within minutes of a cat entering the room. Even after a cat has been removed from a particular environment, however, it can take months before the existing amount of cat allergen is reduced. It has been estimated that it may take up to five years for the levels of cat allergens in a mattress to fall to those equivalent to a cat-free home. Any soft furnishings, such as carpets or sofas, may continue to serve as a reservoir of cat allergens even after a cat has removed.

There is no such thing as a truly non-allergenic breed of cat because all cats produce dander. On an individual basis, a person may also react less to a particular pet than they do to other cats of the same breed. In general, male cats will produce more allergens than female cats. Some breeds of cats may be less troublesome to allergic owners because they shed less fur, which invariably becomes coated in cat allergen, and because animal fur also collects dust, mould, pollen, and other allergens. The sphynx, Cornish rex and Devon rex are all breeds of cat that have the benefit that they shed little or no hair.

Your doctor can administer an allergy skin test if you suspect that you are allergic to cat allergen. The Skin Prick Test involves a small drop of allergen solution being put on the skin of the forearm and being pricked using a fine point. If the person has antibodies to the allergen then a small, itchy bump will appear within ten minutes. This area of skin will quickly settle down once again and return to normal.

Tips to Reduce Cat Allergens

• Try to keep the cat outside for as long as possible or limit its access to certain rooms in the house. The cat should be kept out of the bedroom at all times.
  
• Ensure that your home has adequate ventilation by opening windows or using air cleaners or exhaust fans. HEPA (High Efficiency Particle Arresting) air cleaners can also help but cat allergen protein particles may be so small that they pass through the filters.
  
• The quicker that airborne allergens can be dissipated, the less allergen will be left floating in the room. Because cat allergen can travel through the air, it can be transported through the air ducts of heating systems that use hot air. Ensure that your home has adequate ventilation by opening windows or using air cleaners or exhaust fans. HEPA (High Efficiency Particle Arresting) air cleaners can also help but cat allergen protein particles may be so small that they pass through filters.
  
• Cat dander settles onto soft furnishings, being released back into the air by movement. Carpeting can be replaced and upholstered furnishings can be replaced with furniture that wipes clean. Nylon and synthetic fabric surfaces attract allergens more than natural fabrics do. To put it into perspective, a carpeted floor will accumulate allergens at a rate nearly 100 times more than that of a polished floor. Cat allergen can be found on walls and other vertical surfaces so it helps if these are also washable.
  
• Wash your cat. Bathing will remove much of the surface allergen present on their fur. Kittens are usually more open to being washed while cats can be gradually conditioned to the experience. Don't wash your cat more than once a month because this can dry out the skin, causing your cat scratch more and produce even more dander.
  
• Feed your cat a well balanced diet that includes some natural fat. This will help make your cat's skin less dry and will cause less shedding.
  
• Wear a face mask when changing the cat litter, as cat urine contains allergens, or brushing the cat. If possible, get someone else to do this for you. Try to buy non-deodorized cat litter that produces very little dust.
  Wash your hands after contact with the cat to remove allergens, especially before touching your face.
  
• Wash your clothes to remove the cat allergens that have adhered to them.
  
• If you experience a rash after being licked by your cat, try to avoid such contact in future as the mouth is the primary source of allergenic protein.

Dogs

Dogs have a number of protein particles in their saliva and skin that can provoke allergies. This seems to occur more frequently in the longer-haired breeds of dogs but this is still less common than cat allergy because cat allergens are much more likely to result in the sensitisation of people. Breathing in dog allergen particles can set off an allergic reaction, as can being licked by a dog, because this brings you into direct contact with the dog's saliva.

The most common route for the allergen is when the dog deposits its saliva on its fur or skin during grooming, only for the saliva to dry and leave behind the protein antigen that trigger allergies. These allergens then become airborne because they are microscopic and lightweight and, once in the air, they can easily spread to clothes, carpeting or furnishings.

There are a number of reasons, however, why dog allergy is less prevalent than cat allergy. Firstly, dogs are usually kept outside or spend more time outdoors than cats. Secondly, dogs are more likely to be kept out of the bedroom. Thirdly, most dogs are washed regularly, which is less common in with cats. Many of the tips described above for the reduction of cat allergens are also applicable to dog allergies.