Dog Penis – Anatomy, Characteristics and Diseases

When looking at the genital area of ​​a male dog, what you see is the foreskin. The foreskin is the skin, covered with hairwhich protects the dog’s penis.

The dog’s penis is made up of the root, shaft and glans:

  • The root of the penis is what attaches the penis to the ischial arch.
  • The shaft is the widest part of the penis. It is in turn divided into two parts: the corpus cavernosum, which is the largest and fills with blood during erection, and the corpus spongiosum.
  • The glans is the distal part, that is, the extremity, where the entrance to the urethra is located.

The penis of dogs is a musculo-cavernous, just like the penis of cats and horses. Unlike fibroelastic type penises (ruminants and pigs), this type of penis fills with blood upon erection. In the image below you can see the anatomical differences of the penis of different species.

Does a dog’s penis have bones?

Yes, the dog’s penis has a bone called the “penile bone”. The penis has essentially two functions: to eliminate urine and semen (during mating). In addition to this important structure, the dog’s penis has a urethra which is partly protected by the penile bone, one of whose functions is to protect the urethra from possible trauma.

Occasionally it is possible to see a small yellowish colored discharge, called smegma, coming out of the dog’s penis, don’t worry, this is completely normal.

Dog Penis - Anatomy, Characteristics and Diseases - How is a Dog's Penis Like?

Dogs, unlike female dogs, do not have a specific time when their heat is triggered. Indeed, if there is a female in heat, the males can mate at any time of the year. During copulation, the dogs stay glued to each other for a few minutes, but… why? How does a dog’s penis work?

This is because of a mechanism that prevents urine and semen from mixing in the urethra. At the base of the penis is a structure called bulb (bulbus glandis) which, for the penetration to go well, grows considerably in order to fit into the cervix of the female dogs, which has a pit shape.

On average, copulation in dogs lasts 30 minutes. The dog ejaculates in small portions because he has a “dripping” ejaculation and that is why it is so important that the two animals stick together during the different phases of ejaculation. Therefore, as you will have understood, dogs should never be forcibly separated during copulation, because in addition to preventing the good reproduction of the animals, you could hurt them.

Dog Penis - Anatomy, Characteristics and Diseases - How the Dog Penis Works During Mating

Diseases and problems related to the dog’s penis can have many different origins. They can be caused by trauma, such as fights, or by the presence of foreign bodies. Diseases of the dog’s penis generally appear as a result of a viral infection, the presence of bacteria and a tumor.

Here is some of the symptoms of dog penis diseases :

  • always out
  • Bleeding
  • Swollen foreskin
  • Color change (should be pink or reddish)
  • Pus
  • Excessive licking of the genitals

If you observe any of these symptoms, your dog may have one of the following problems:


Phimosis is the dog’s inability to push out his penis because the opening has become too small. Usually, due to the inflammation, the dog excessively licks the area and dirt accumulates there, causing an infection.

This problem is usually only noticed by guardians when the dog tries to breed and fails. But the problem can be identified by observing other symptoms, such as:

  • Inability to urinate
  • Accumulation of urine on the foreskin
  • Excessive licking

This condition can be congenital or acquired. The only way to treat phimosis in dogs is through surgery, which aims to widen the opening of the foreskin so that the penis can exit smoothly.

This is a very serious problem, because the dog can force his penis out, but he will then be unable to retract it.


Paraphimosis is the exteriorization of the penis without it being able to return inside the preputial cavity. The causes can be the same as for phimosis, which is a small hole in the foreskin that allows the dog to protrude its penis during erection, but prevents it from coming back into place. However, other causes, such as trauma, problems with the musculature of the foreskin, reduced size of the foreskin, and even neoplasms (such as transmissible venereal tumor), can cause it.

Symptoms are: a penis always sticking out, which may seem normal but over time can cause problems, such as cuts and cracks. Therefore, if your dog has a swollen penis and is unable to retract it, you should definitely get him to the vet as soon as possible.


One of the most common problems a dog’s penis can suffer from is trauma. Trauma can occur during copulation (for example, trying to separate two dogs that are stuck together) or during an accident that injures the dog’s penis.

Another very common cause of injury in this area is the intrusion of foreign bodies, such as dried grass entering the preputial cavity or even a urinary stone.


Balanoposthitis in dogs is an inflammation of the glans and the lining of the foreskin. Balanitis is an inflammation of the glans and posthitis is an inflammation of the foreskin. In most cases, these two processes occur simultaneously and are therefore called balanoposthitis.

Balanoposthitis is very common in dogs and its symptoms are:

  • Pus on the foreskin
  • Excessive licking of the area

The causes can be many, but the most common is the presence of opportunistic bacteria which usually live in the dog’s penis.

Transmissible venereal tumor

TVT (transmissible venereal tumor) in dogs is one of the most common neoplasms. This tumor is sexually transmitted and can affect both males and females. During mating, small lesions may appear on the penis and vagina, which allow tumor cells to enter.

The symptoms are: nodules in the genital area, bleeding and even an obstruction of the urethra, which prevents the dog from urinating normally.

The treatment is generally based on chemotherapy and/or radiotherapy sessions. The prognosis depends on the case, but if detected in time, treatment is usually very effective.

Dog Penis - Anatomy, Characteristics and Diseases - Most Common Dog Penis Diseases


Dog Penis – Anatomy, Characteristics and Diseases

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