Perhaps it was during a relaxing belly rub, or just as the two of you were about to head to the local dog park together. Regardless of the situation, it can be awkward when a dog’s private parts become visible.

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What is that?

You can’t normally see a dog’s penis – what is visible is a protective sheath called the prepuce. It’s not until your dog becomes aroused that it emerges and is visible. Here are the main reasons it will happen:

Sex and play

Mounting and humping are normal behaviours, and both may result in your dog’s penis becoming exposed. Your dog may mount and/or hump objects for several reasons, including sexual activity or in responding to stressful, exciting and boring situations. Puppies on the other hand discover their own strength and social standing through non-sexual play humping.

If you think your dog’s constant humping is a problem, consider visiting your local Greencross Vets to discuss desexing. Keep in mind, however, that neutered dogs may still display erections, and hump things, from time to time. You can also see our article on puppy humping for other good pet care ideas.


Arousal isn’t just confined to sexual behaviour. Anything that excites your dog excited can give him a slight erection, which will still result in part of his genitals emerging from the prepuce. That may include during belly rubs, when you’re about to give him his favourite food, or if he hears the jingle of his walking lead. The smaller your dog’s prepuce, the more chance his penis will come into view.

If you have important guests coming around, and you don’t want your dog to display his erection in front of them, exhaust him with a run, a game of fetch or tug of war before they arrive.

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Medical conditions

If your dog’s erection hasn’t subsided after a few hours, your dog may have paraphimosis, a condition which means he suffers from an inability to retract his penis back into his sheath, and damage to the exposed tissue can occur. In this case, you should consider taking him to your local Greencross Vets.