Hi, I'd suggest anyone with a potential horsehair or other fibre allergy gets a scratch test done at their GP's surgery: this is good enough to see if you're allergic to the substance: a small scratch is made on the arm and a tiny amount of the putative allergen is applied: if an itchy red bump or wheal comes up, you're allergic, if not you're OK. Another test is called a RAST test, but this done by an allergist at your hospital. See the GP first!

Rob.