While cats are the most popular pet in the United States, their biggest behavioral problem, house soiling, is very unpopular with their owners. Studies report that house soiling is the leading cause of relinquishment of cats to shelters. Understanding the underlying motivation for house soiling is critical in creating a targeted treatment plan and helping owners becoming more tolerant and understanding of their pets behavior. Dr. Jacqueline Neilson, owner of the Animal Behavior Clinic in Portland, Ore., talks about ways to eliminate feline house soiling.