Living with dogs means living with, or at least ignoring, their somewhat gross 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 behavior that is incredibly embarrassing, especially around polite company. It’s the occasional appearance of his dog penis — or what’s politely referred to as a male dog’s “lipstick” or the “red rocket.”

There’s nothing like having friends and family over and everyone stops talking mid-sentence because a dog penis has appeared. Trust me, I know. My German Shepherd Dog Forest is well known for this.

So what’s up with a boy dog’s you-know-what? Why does it always appear at inappropriate times? And why does your dog have a fascination with other dogs’ private parts? Let’s answer a few of your questions about the dog penis.

A dog penis in prepuce.

A dog penis in prepuce. Photography courtesy Jessica Pineda.

Basic Terminology — What Exactly is a Red Rocket?

Since we humans are uncomfortable with saying the “p” word, colloquial terms like “dog lipstick” or “red rocket” are popular substitutes for the term dog penis. Those terms describe a dog’s actual penis, which, for the most part, stays in the prepuce. (That’s the furry area you thought was a dog’s penis in more innocent times.)

“Red rocket” or “lipstick” is a pretty apt term: A dog’s erection generally ranges from pink to red in color, and is stiff as well. It’s shape is similar to the top of a rocket or lipstick, hence the nicknames for a dog penis.

Why Does the Dog Penis Come Out?

You probably already know that answer to this, but the dog penis comes out when a dog is aroused.

No, not like that, at least in a non-breeding context. 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. Arousal can be something as simple as your boy dog getting excited about a training session, which happens with my dog, Forest.

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 just ignore it and move on,” she says.

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

Other Times You Might See a Male Dog’s Lipstick

A male dog, neutered or otherwise, may get erect if he mounts another dog, whether they’re male or female, and starts humping the other dog. This humping behavior is usually innocent in nature. “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 of Sacramento, California. “That’s usually play behavior.”

Typically, dogs start humping if they get overly excited or stressed and haven’t learned how to properly channel those feelings. As mentioned, the behavior itself is innocent, and if the other dog doesn’t like it, they’ll tell your dog. However, that kind of behavior is embarrassing or offensive to lots of people, so if your dog is known for humping, train your dog not not to hump other dogs.

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.

Weird Things the Dog Penis Does

One of the other times a dog penis makes an appearance is if a female dog in heat allows an intact male dog to mount her. (For most of us, since we typically spay and neuter our dogs, we’ll never see that.) This is also the time when a dog’s penis does something unique.

“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 for a short period of time until the swelling goes down. This is often referred to as a male dog “tying” a female.

What’s Up With Dog Penis Discharge?

Every now and then, you might see yellowish-greenish discharge or pus coming out of your dog’s prepuce. According to, that discharge is a mix of cells and lubricant that keeps the dog penis protected while in the prepuce. You shouldn’t see this discharge all that often and only in small amounts.

However, if you are seeing a lot of discharge and it’s accompanied by your dog licking his privates excessively, it may indicate a serious health problem such as a urinary tract infection or canine cancer. And if the blood is mixed with the discharge, that’s a signal to get your boy to a veterinarian ASAP.

Can Neutered Dogs Still Get Erect?

The short answer? Yes. A neutered dog can’t get a female dog pregnant, but since dog arousal isn’t always tied to sexual situations, the notorious dog penis can and will make an appearance.

What’s Up With Dogs Licking Other Dogs’ Privates?

It’s bad enough you’ll sometimes have a male dog exposing his dog penis for everyone to see. If you’re like me, and you have two dogs, one who happens to be a spayed female, you’ll have the added joy of your dog deciding it’s a great time to starting licking your other dog’s private parts. My sister’s family has got to experience this on several occasions, much to my utter mortification.

So, why do dogs do this? It’s actually fairly 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 perfectly normal dog-on-dog interaction; however, there’s always one or two dogs that seemingly go overboard and won’t put their noses or tongues away. This can lead to uncomfortable situations between pet parents, some who might not understand what is going on. You’ll have to talk to the other owner to determine his or her comfort level with what’s happening.

“Some dog owners are of the mind that they should let the dogs sort it out. The other 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.”

So there you have it: Your guide to everything dog penis related. You may now pretend you never read this article.

Thumbnail: Photography by Kryder17/Thinkstock. 

This piece was originally published in 2017. 

Jessica Pineda is a freelance writer who lives in Northern California with her two German Shepherds, Forest and River.

Read more related articles on