Why does my neutered dog still mark indoors?

A dog neutered later in life, after months or years of established marking, has often built a strong learned habit layered on top of the original hormonal drive, and removing the hormones does not automatically erase a behavior pattern that has become routine.

Treat continued marking after neutering with the same active training used for any marking case, supervision, interrupting the pre marking posture, and thorough cleaning of previously marked spots, since the behavior itself, not just its hormonal trigger, now needs direct attention.

Before treating this purely as leftover habit, check whether anything in the household actually changed around when the marking resumed, a new piece of furniture, a visiting dog, a rearranged room, since those can restart marking in a neutered dog just as easily as in an intact one. Marking that starts suddenly after months of being fully house trained is worth investigating as a specific trigger rather than assumed to be old hormonal behavior resurfacing.

Dogs neutered as adults, particularly those over two years old at the time of surgery, are statistically more likely to retain some marking behavior than those neutered before six months, simply because the habit had longer to become established beforehand. This does not mean training will not work, only that it may take a bit longer, often four to six weeks of consistent supervision rather than two.

If marking is frequent, involves larger amounts of urine than a typical mark, or is paired with straining or visiting the water bowl more than usual, ask a vet to rule out a urinary tract infection or another medical cause, since those can closely resemble a behavioral marking pattern.