Male dogs will start to make their territory around the age of 4 moths. “Marking” is when a male dog hikes his leg to urinate. Males tend to mark most objects that stand upright such as shrubs, trees, fences, and even patio furniture. Unfortunately they can also begin to mark their territory inside even if they are housebroken if another male comes into the home. This is a good reason to have your male neutered around the age of 4 months unless he will be used for breeding.