Probably one of the most common allergies, this site talks about diagnosis, causes such as dog hair that carry dander, and treatment.

This was a fairly good overview of pet allergies, but incomplete. It mentions bathing your pet weekly, but most people allergic to pets find that a quick daily sponge bath is much more effective. This method was not mentioned. There are sprays that can be purchased that also work much better than a weekly bath. These too were not mentioned, so I'd have to lower my rating accordingly.