When Do Dogs Start Marking Territory. This usually happens when pups are anywhere from 6 months to a year in age. Dogs use their urine (and sometimes feces) to mark areas they consider to be theirs.
Both male and female dogs urine mark. Sexual maturity typically spurs an urge to mark in an attempt to attract a mate, which can occur at around 6 months old. Keep in mind that dogs that have been neutered or spay can mark territory, although it’s less frequent.
