My 1 1/2 yr old male chihuahua (not desexed) has recently started peeing on my pillow, and the mattress?

Sometimes around the age of 2, the males start to make their territory. Is he peeing a lot or just sprinkling the area? If he is peeing a lot, it could be a urinary tract infection. If just a sprinkle, it's turf marking. Neutering may or may not correct this.