Dog Penis Health Guide: Everything You Need to Know

PetMD Editorial
October 05, 2017
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Reviewed and updated for accuracy on February 3, 2020, by Dr. Jennifer Coates, DVM

Every part of the body can be injured or affected by disease, and this includes a dog’s penis. Problems affecting the penis are uncomfortable and may be a sign of a potentially serious health condition.

This guide will help you determine if your dog’s penis is healthy or if you need to make a call to your veterinarian.

Dog Penis Health: What Is Normal?

In order to recognize when something is wrong with your dog’s penis, you need to know what normal looks like.

Most of the time, what you see on the outside of a dog’s penis is actually the prepuce or sheath—the skin and other tissues that surround the non-erect penis. The penis itself is covered with a mucous membrane, which makes it appear moist and bright pink or red.

A small amount of yellowish-white or even slightly green-tinged discharge can collect around the opening to a dog’s prepuce. This is called smegma and is normal.

The canine penis is rigid even when not erect due to the presence of a bone called the “os penis.”

Two glands called the “bulbus glandis” are located on either side of the base of the penis. When a dog becomes aroused, the bulbus glandis swell with blood, creating two readily visible bumps.

Erections can occur even if a dog is neutered, and full erection may result in the entire engorged penis and bulbus glandis extending outside of the prepuce.

It’s important to note that a dog’s erection may last for just a few minutes or up to an hour or so.

Is My Dog’s Penis Infected?

Pet parents often worry that their dog’s penis is infected. Sometimes what you might think is pus—a sign of infection—is just normal smegma.

Some dogs, even when healthy, will produce a surprising amount of smegma, and they will often lick their penis to remove it.

However, drainage from the prepuce and excessive licking are also the most common symptoms of infections of the penis and/or sheath, so determining what is normal and what is potentially problematic can be difficult.

You should make an appointment with your veterinarian if:

  • Your dog is licking his penis more than he typically does

  • Your dog seems listless or otherwise ill

  • The discharge has increased in quantity or changed in color

Why Is My Dog Licking His Penis?

A dog will lick his penis to help keep it clean, and probably also just because it feels good.

Some dogs will lick or self-stimulate in other ways to the point where they get erections, even if they are neutered. It’s best to simply ignore this behavior unless you also notice problems with your dog’s penis or changes in his overall health.

Excessive licking, especially when it’s associated with symptoms like increased drainage, pain, or lethargy, can be a sign of infection, injury, or other conditions affecting your dog’s urinary or reproductive tract.

Call your veterinarian if you have any concerns.

Why Is There Blood Coming from My Dog’s Penis?

Blood may be seen coming from a dog’s penis as a result of wounds to the penis or prepuce, conditions affecting the urinary tract (infections, tumors, bladder stones, etc.), blood-clotting disorders, and diseases of the prostate gland.

The most common cause of bloody discharge from the penis in an unneutered male dog is benign prostatic hypertrophy (BPH), a non-cancerous enlargement of the prostate gland associated with exposure to testosterone.

A veterinarian can often determine whether a dog has BPH by feeling the prostate gland during a rectal examination. Neutering will cure most cases of canine BPH.

Any dog who has blood coming from his penis should be evaluated by a veterinarian.

Why Is My Dog’s Penis Stuck Out?

Dogs will get occasional erections, even if they are neutered.

If your dog’s penis becomes erect and visible for a period of time but then returns to being fully enclosed within the prepuce and all else seems to be normal, you probably don’t have anything to worry about.

That said, dogs will sometimes have persistent erections or can’t retract the penis back into the prepuce due to hair that encircles the penis, neurologic problems, prostate disease, or anatomical abnormalities.

If the penis is discolored or the normally moist tissues that cover it are becoming dry, bring your dog in to see a veterinarian immediately.

Difficulties with urination and permanent damage to the penis can occur in these cases without rapid treatment.

Is My Dog’s Penis Swollen?

A dog’s penis will become swollen during a normal erection. The enlargement of the bulbus glandis is especially obvious since it causes sizeable bumps to form on either side of the base of the penis.

As long as a dog’s swollen penis returns to its normal size within an hour or so and the dog seems to feel fine otherwise, no veterinary treatment is usually necessary.

But, if your dog’s penis remains enlarged for an extended period of time, or if you notice any other worrisome symptoms like lethargy, poor appetite, discomfort, or abnormal discharge from the prepuce, you should call your veterinarian for advice.

Problems like infections, injuries, and tumors can also make a dog’s penis appear to be swollen.

Is This Color Normal?

A dog’s non-erect penis is normally enclosed by his prepuce, which is covered by skin and hair that looks similar to that found elsewhere on his body.

When visible, the penis itself is usually pink or red, but can become a darker purple during an erection. The color should return to normal after the erection is over.

A small amount of yellow-white or slightly green-tinged discharge from the end of the prepuce is also normal. If you notice changes to the coloration of your dog’s prepuce, penis, or preputial discharge, make an appointment with your veterinarian to rule out infections, injuries, and other conditions.

What Is This Discharge Coming from My Dog’s Penis?

A small amount of yellow-white or slightly green-tinged discharge from the end of your dog’s prepuce is usually the normal smegma, which is made of dead cells and other material that collects within the enclosed space of a dog’s prepuce.

However, other types of discharge or a discharge that comes directly from the penis itself is often associated with a health problem.

Dogs with bloody or pus-like discharge from the penis or prepuce should be seen by a veterinarian. Possible diagnoses include:

  • Traumatic injury

  • Foreign material lodged within the prepuce

  • Infection of the urinary or reproductive tract

  • Cancer of the urinary or reproductive tract

  • Urinary tract stones (uroliths)

  • Prostatic disease

  • Blood-clotting disorders

  • Anatomic abnormalities

  • Erectile disorders

What Is This Rash on My Dog’s Penis?

The skin-covered prepuce that surrounds a dog’s penis can develop rashes, just like any other area of the body. Because the prepuce touches the ground whenever a dog sits or lies down, it frequently comes in contact with irritants, allergens, and insects that may bite.

Parasites or skin infections can also cause rashes on a dog’s prepuce.

Giving your dog a bath using cool water and a gentle soap might help if your dog’s rash developed due to contact with an allergen or irritant.

Rashes that are severe, produce significant discomfort, or persist for more than a day or two should be evaluated by a veterinarian.

What Is This Lump, Bump, or Growth on My Dog’s Penis?

It is normal for lumps to form on either side of the base of a dog’s penis during an erection. These should disappear when the erection ends. Also, it is not unusual to find nipples on the skin on both sides of the penis.

Other lumps, bumps, or growths that persist on or around a dog’s penis are not normal and may be associated with injuries, infections, the presence of foreign material within the prepuce, inflammation, cysts, or tumors.

Make an appointment with your veterinarian if you have any concerns about your dog’s penis health.

By: Jennifer Coates, DVM

Featured Image: iStock.com/Vincent Scherer