Allergies to animals are common and very troublesome. Some people simply cannot give up their pets, their horseback riding, or their friends who have pets. And yet exposure to a dog or cat can cause a sensitive person quite a serious reaction. For such people, a combination of treatment and partial avoidance is the best approach. In some cases, the allergy is just too strong, and the pet must be placed in a new home.

Allergies to cats can be particularly severe. There are people who cannot be in...