Remedy for Allergy to Cats?

Don't touch it, don't let it in your house. If you visit the neighbour, sit on a wooden chair (not covered with fabric) and take your allergy pills with you, just in case. Some cat owners are very conscientious about the hair, others, not so much. If the owner visits you and has cat hair on hands, face or clothing, perhaps sit outside or ask that person to sit on a wooden chair and not touch your furniture. If you're the kind of person who likes to hug favourite people, avoid hugging your neighbour (and explain the reason).

If the cat is let loose and prowls in your yard, first ask the owner to keep the cat on a leash and - depending on your relationship with the owner - if your neighbour refuses, buy yourself a water gun (the strong kind used by kids playing at the lake) and shoot the critter with water: the cat will get the message to stay away from your yard.