A dog marks in the house due to territorial behavior, anxiety or fear, illness or lack of house training. The first step in solving the problem is a trip to the veterinarian for a health evaluation. Neutering a dog reduces the chances of developing territorial marking behaviors in the house.

Unneutered dogs, both male and female, are likely to exhibit territorial marking behaviors. In dogs neutered late in life, those behaviors become ingrained habits that are hard to break. To reduce the risk of marking in the house, neuter a dog as young as the veterinarian recommends, usually before 6 months of age.

Health problems, such as kidney disease or urinary tract infections, cause dogs to urinate in the house. A veterinarian should immediately evaluate a dog who suddenly develops this habit to rule out medical causes. Fearful or anxious dogs may develop marking behavior. A veterinarian may prescribe medications to help calm a fearful dog while the root of the fear is eliminated. Seek help from a behaviorist for anxiety that persists.

Sometimes, a dog marking in the house means that it lacks proper house training. Take the dog outside frequently, and reward it for urinating outdoors. Consult a dog trainer for assistance with house training if necessary.