Only you know your pets and their habits, and this knowledge will go a long way in preventing your furniture from long-term, irreversible damage. As you begin, here are a few things to keep in mind.
Cats, or dogs, who scratch can cause significant damage and leave lasting marks. Choose a tightly woven fabric to resist damage or a patterned one to hide marks.
Licking / Chewing
An obsessive licking habit can leave unattractive wet spots on your upholstery that can resemble water marks, while a chronic chewer can wreak havoc on exposed wood. Be wary of microfiber type fabrics, as they are more prone to water marks.
Like it or not, your pet's hair will find your furniture. If your companion sheds, consider either a patterned fabric or one that matches your pet's coat.
Puppies and kittens can be difficult to house train and messy accidents are bound to happen. Fabrics that are easily wiped will help in this case, as well as ones that don't retain odors.