* Protection: The hair can provide some protection against friction and irritation during mating. It acts as a buffer between the sensitive skin of the penis and the vulva of the female dog.
* Sensory input: The hair follicles contain nerve endings that can provide some sensory input, which may help the dog during mating.
* Scent marking: The hair can also help to spread the dog's scent, which can be important for attracting mates.
While the hair on a dog's penis is considered normal, it's important to note that it shouldn't be excessive or clumped together, as this could be a sign of an underlying medical condition. If you notice any changes in your dog's penis, it's always best to consult with your veterinarian.