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Pictures of Dog Bulbus Glandis: What it Looks Like on Dogs

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This article was updated on April 30th, 2023

The bulbus glandis is a normal part of male dog anatomy. Sometimes visualized as two enlarged, round swellings under the skin on either side of the pen*s, the bulbus glandis is made up of erectile issue. When a male dog is excited, blood flows into the bulbus glandis causing the characteristic engorgement of these round structures.

Have You Seen This On Your Dog?

Bulbus Glandis is a part of the dog reproductive system that is present in male dogs. It is located at the base of the pen*s and swells during arousal, causing the dog’s pen*s to enlarge and lock into the female’s vag*na during copulation.

happy dog getting a belly rub

As the owner of a male dog, you may have just discovered Bulbus Glandis for the first time: it may be a surprise or even a cause for concern! You may be concerned about your dog’s health or feel uncomfortable with the visual appearance. However, it’s important to note that this is a natural part of a male dog’s anatomy. In this article, we will review pictures & explain what is, and what isn’t, normal, so that you can better help your dog.

How Do You Recognize Bulbus Glandis? [With Pictures]

The bulbus glandis, when engorged, appears as:

  • symmetrical,
  • round,
  • firm
  • located on either side of the pen*s.

They are further cranial (towards the head) than the testicles and can appear in both intact and neutered male dogs. When the dog is no longer excited, they will completely disappear.

Pictures of Bulbus Glandis on Dogs

The bulbus glandis, when engorged during mating, serves to retain the male’s pens in the vagina of the female, just before, during, and after ejaculation. This “tie” during mating may last from 20 minutes up to an hour. It is completely normal for the bulbus glandis to engorge and be externally visible on all male dogs, even if they are neutered.

WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]

Below are two pictures of bulbus glandis on dogs:

Is What I am Seeing Swollen Bulbus Glandis – or is it Something Else?

The best way to know if the structure you are seeing in your male dog’s groin is the bulbus glandis is to ensure that the structure disappears from visibility when the dog is no longer excited.

If the bumps persist, if one side is larger than the other, if there is just one mass, or if the pen*s is stuck outside of the prepuce, your dog needs to be seen by a veterinarian as soon as possible.

These different appearances could indicate an injury or tumor:

1. Hernia

2. One-sided mass

If one side is larger than the other, if there is just one mass, please reach out to your veterinarian.

Is there anything you can do at home if you notice a swollen bulbus glandis?

If your male dog has an engorged bulbus glandis, there is nothing that you need to do. The condition is not painful for the dog and is a perfectly normal occurrence.

When to call your veterinarian

If the engorgement of the dog’s bulbus glandis persists for longer than two hours or if the pen*s is outside of the prepuce, you should seek veterinary care.

Frequently asked questions

Why do dogs have a bulbus glandis?

This structure is a normal part of male canine anatomy. The bulbus glandis engorges with blood during mating to retain the pen*s inside the female’s vagina before, during, and after ejaculation.

Does a swollen bulbus glandis cause any pain for the dog?

Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.

No, an engorged bulbus glandis is not painful for the dog.

Does neutering your dog remove the bulbus glandis?

No, the castration (neuter) surgery consists of surgically removing the make dog’s testicles. The bulbus glandis is a normal anatomical feature and will be present in both intact and neutered dogs.


  • Dr Whittenburg, Hospital Director

    Dr. Jamie Whittenburg is a Veterinarian Director at 'Senior Tail Waggers' and Director and Owner of Kingsgate Animal Hospital, a full-service animal hospital in Lubbock, TX. She graduated from Kansas State University's College of Veterinary Medicine (DVM) and has over 17 years of experience working as a veterinarian & hospital director.

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