Persistent Mullerian Duct Syndrome in Dogs

Category: Urinary & Reproductive
Breeds documented: 1
Published sources: 4

Overview

In some male dogs, tissues that normally disappear before birth remain and form a uterus and other female reproductive structures. This is called persistent Mullerian duct syndrome, or PMDS. The dog may look typically male on the outside, so the internal difference can be missed. Some affected dogs also have testicles that remain inside the body instead of reaching the scrotum, increasing the risk of infertility and testicular tumors.

Signs to watch for

One or both testicles missing from the scrotum
Blood appearing in urine in some affected dogs
Bloody discharge from the penis in some affected dogs

Develops before birth; urinary or tumor-related complications may appear later.

When to get help Book a vet visit if a testicle is missing from the scrotum or blood appears in urine.

Diagnosis and tests

Ultrasound can reveal unexpected uterine tissue or fluid-filled structures near the prostate. Surgery and examination of removed tissue can confirm the internal reproductive structures. A DNA test checks for the PMDS variant known in Miniature Schnauzers, but other causes of undescended testicles exist and the same test may not explain cases in other breeds.

Breeds with documented risk

1 breed

By breed size

1 Small

Miniature SchnauzerSmall · Terrier Group

Inheritance

Not yet known
None of the sources we use states how this is inherited in dogs yet.

We've gathered what published sources say about this condition, so you can talk it through with your vet. It isn't veterinary advice: you and your vet know your dog best.