I hate to destroy a few well-worn myths, but most people allergic to cats are allergic to the epithelium (skin, saliva, mucus), not the hair, so the length, or even absence, of hair may make no difference to an allergy sufferer. Many people think they are allergic to cats, when in fact they are sensitive to the dust mites and pollens trapped in the fur. Or they are allergic to cats and the junk in their fur. They get a shorter-haired, or no-haired, cat, and notice their allergies are diminished, not realizing that it is only because their new cat carries fewer allergens. And it is possible to be allergic to a new cat, but not your old one. Actually, you are allergic to your old one, you just don't notice it anymore, because you have built up a tolerance. This is called desensitization, and is the theory behind allergy shots. You will eventually build up a tolerance to the new cat too, although if you have a severe allergy it may never completely disappear. And immunology is in no sense a "black art", and a simple skin test will identify any allergen that a person is sensitive to, as well as eliminate any that they aren't. I think the "black art" attitude stems from the fact that alot of people think any type of physical reaction is an "allergy" when in fact they are not. An allergy is simply, and strictly, an improper immune response to an otherwise harmless protein. In other words, my body has somehow gotten the idea that the proteins in cat epithelia are nasty disease causing organisms, so it sends out an immunizing attack. So things like "sun" allergies are misnomers. There may well be some reaction or sensitivity, even severe, but it is not of an allergic nature. And this is where alot of the "black art" comes in, too, because these type reactions are alot harder to pin down.

Anyway, I'll get off my soapbox now...