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Dog Penis Behavior: Everything You Wanted to Know

Here’s everything you want to know but didn’t want to ask about the dog penis — from why the lipsticks come out to dog penis discharge.

Written by: Jessica Pineda

Last Updated on May 24, 2024 by Dogster Team

dog penis in prepuce

Dog Penis Behavior: Everything You Wanted to Know

Living with dogs sometimes requires ignoring their somewhat disturbing behaviors. Whether that’s dogs sniffing other dogs’ butts or eating garbage, it’s all a part of parenting canines. A male dog, however, has one incredibly embarrassing behavior, especially around polite company. It’s the occasional appearance of his penis or what’s politely referred to as “lipstick” or the “red rocket.”

There’s nothing like having friends and family over, but it’s embarrassing when everyone stops talking mid-sentence because your dog is flashing them. If you have a German Shepherd Dog, you’ve probably seen this several times. So, why do they do it? Why does it always appear at inappropriate times, and why is your dog fascinated with other dogs’ private parts? In this article, we’ll discuss the male canine’s reproductive organ and why they enjoy displaying it.

Warning — some photos ahead are graphic!


Basic Terminology for the Dog Penis

Since some are uncomfortable with “penis,” colloquial terms like “dog lipstick” or “red rocket” are popular substitutes. “Red rocket” and “lipstick” are apt terms. A dog’s erect penis is generally pink or red and resembles lipstick or a tiny red rocket.

Why Does the Dog Penis Come Out?

When your dog is aroused, his penis becomes erect, but it doesn’t always occur because he’s sexually excited. As veterinarian Dr. Eric Barchas explains in his article Why Do Dogs Keep Showing Us Their “Lipsticks,” arousal is a general term for anything that excites a dog. His arousal can be as simple as getting excited about a training session.

Awkward as it might be to have a dog’s lipstick appear when you’re with friends and family, there’s nothing to worry about, according to Susan Newell, owner and lead trainer of Animal Minds Behavior and Training in Rancho Cordova, California. “The best thing you can do is ignore it and move on,” she says.

A dog penis, aka a dog lipstick or a dog red rocket, can come out for a few different reasons.
A dog penis, aka a dog lipstick or a dog red rocket, can come out for a few different reasons. Photography courtesy Jessica Pineda.

Ignoring it is good, as once the excitement wears off, a dog penis will slip back into the prepuce. Ignoring it means you’re not accidentally rewarding or encouraging your dog’s reaction.

Other Reasons Your Dog May Get Erect: Humping

A male dog, whether neutered or intact, can get erect if he mounts a male or female and starts humping the other dog. This humping behavior is usually innocent. “This isn’t for sexual reasons. They’re not trying to copulate or masturbate,” says Dr. Atif Wardany, the veterinarian and owner of Mobile Pet Hospital in Sacramento, California. “That’s usually play behavior.”

Typically, dogs start humping if they get overly excited or stressed and haven’t learned how to channel their feelings appropriately. If the other dog doesn’t like it, they’ll tell your dog. However, it’s embarrassing or offensive to some people, and you can train your dog not to hump other dogs.

Other Reasons Your Dog May Get Erect: Mating

The dog’s penis will also appear if a female dog in heat allows an intact male dog to mount her. Since most of us spay and neuter our dogs, we’re unlikely to see them mating with other pups. When a male mounts a female, his penis

“A dog’s penis has a bone in it, and in the middle of the bone, there is a gland inside it that swells up when the male’s copulating,” Dr. Wardany explains. “The purpose is to keep the penis inside the female.” Once that happens, the dogs are stuck together briefly until the swelling goes down. This is referred to as a male dog “tying” a female.

What To Do If Your Dog’s Penis Has Discharge

Occasionally, you might see a yellowish-greenish discharge or pus coming out of your dog’s prepuce. It’s a mix of cells and lubricant that keeps the penis protected while in the prepuce. You shouldn’t see the discharge often; if you do, it’s only a small amount.

However, if you see a lot of discharge and it’s accompanied by your dog licking his privates excessively, it may be due to a serious health problem such as a urinary tract infection or canine cancer. If the blood is mixed with the discharge, take your dog to the veterinarian ASAP.

Can Neutered Dogs Still Get Erect?

Yes. A neutered dog can’t get a female dog pregnant, but since arousal isn’t always tied to sexual situations, they can still get erect.

Why Do Dogs Lick Other Dogs’ Privates?

It’s embarrassing when your dog flashes your guests, but it can also be awkward when you have two dogs, and one is a spayed female. You’ll have the added dread of watching your pup licking your other dog’s private parts. So, why do dogs do this? It’s relatively normal for male and female dogs to sniff other dogs’ butts, and that sometimes involves licking, too. “The science isn’t entirely clear on what dogs get out of smelling/licking each other in the private area,” Newell says. “However, the theory is the dog can learn the [other dog’s] sex and if they are sexually receptive by doing so.”

Dogs smelling and licking each other’s private areas is a standard dog-on-dog interaction. However, some dogs seemingly go overboard and won’t put their noses or tongues away. That can lead to uncomfortable situations at the dog park since some pet parents might not understand what is going on. You’ll have to talk to the other owner to reassure them that it’s instinctual and nothing to worry about.

“Some dog owners are of the mind that they should let the dogs sort it out. The dog will tell the other dog when they’ve had enough of smelling and licking,” Newell says. “Other times, it’s best to call your dog away if he spends too much time with the other dog.”

Final Thoughts

Male dogs aren’t shy about showing their body parts to the world, but their arousal doesn’t always indicate they’re ready to mate. When they get excited playing or meeting another canine, they have no control over their erections. Unless their behavior is excessive or bothers another dog, it’s unnecessary to intervene. If you’re concerned that your dog’s behavior is unusual, make an appointment with your veterinarian for a check-up.

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