The best fabrics for incontinence issues are Crypton fabrics. Unlike fabrics with a finish on the top of the surface, Crypton fabrics are engineered so that every fiber is encapsulated.
Crypton fabrics resist staining. They never absorb liquids because the liquids cannot penetrate the surface and the seat cushion padding. The fabrics also provide bacterial resistance yet have breathable comfort. They have been used in health care furniture for a number of years but have only been available for home use in the last few years.
Over 1,000 local upholstery shops throughout the United States carry Crypton. They are listed on the Crypton Fabrics Web site at http://www.cryptonfabric.com. Fabrics can also be purchased from the Web store at the same address.
Your only other fabric choice would be vinyl, which will not be as comfortable.