Though your pet is part of the family, a potential landlord might not see it that way. So before you search for a new abode, you need to know why landlords reject pets. After all, knowledge is power.

First, there’s possible damage to the rental property. “Landlords complain that no matter how housebroken a cat or dog is, they still urinate in small spots that can damage the carpet, the rubber pad or even the flooring,” says David Brown, an attorney in Monterey, Calif. and co-author of California Tenants’ Rights. “This may require expensive re-carpeting and perhaps re-flooring.”

Then there’s the matter of size. Most landlords won’t balk at caged hamsters, birds or fish, but renting with cats and dogs — especially large dogs — can be problematic.

“I became an expert at renting a dwelling with pets when I had to find a place to live with a 50-pound Labrador retriever this year,” says Sara Lingafelter, an attorney in Silverdale, Wash.

Although it took Lingafelter two months, she did locate the apartment of her (and her Labrador’s) dreams. She began her campaign by emailing rental agents and apartment managers with the message, “You want me as a tenant.” She added, “I’m a professional, I have lived in the community, I am a good tenant, and I just happen to have a dog. Before you rule me out as a tenant, meet with me and make a decision based on me, not on the dog.”

Another issue is breeds. “Landlords are concerned about the liability factor for dog bites, particularly when renting to tenants with large dogs or dogs known to have aggressive tendencies,” cautions Brown.

Follow Lingafelter’s example and prepare materials to market yourself and your pet to prospective landlords. The Humane Society of the United States’ “Pets for Life” program provides samples of a pet resume, letter of reference from a former landlord and letter of reference from your veterinarian.

On your pet’s resume, include that your pet receives regular veterinary check-ups and has a caretaker when you’re traveling. If your dog has had behavior training, be sure to mention this benefit. And make sure your pet is spayed or neutered. This shows you’re a responsible tenant by preventing unexpected litters.

A pet scrapbook also lets your landlord know how important your pet is to you. Include photographs of your current home, activities you engage in with your pet, and any other photos that characterize you and your pet in a favorable light.

Local Humane Societies have pet-friendly apartment directories, or consult the national organization’s resource for finding pet-friendly apartments for rent across the country.

And when you locate the right apartment and the landlord gives the green light, get the approval in writing. “If the landlord tells you pets are OK, be sure you obtain both his signature and yours before you move in,” says Nancy Peterson, registered veterinary technician and the Humane Society’s program manager in Washington, D.C. “Word of mouth just doesn’t cut it.”