Back

Persistent Müllerian Duct Syndrome

Persistent Müllerian Duct Syndrome is an inherited disorder affecting male dogs, predominantly observed in breeds such as Miniature Schnauzer, Schnoodle, Standard Schnauzer and breeds where remnants of female reproductive organs persist internally despite outwardly normal male anatomy, potentially leading to infertility and requiring careful breeding practices to avoid producing affected offspring.




Affected Genes: AMHR2

Inheritance: Sex-Limited Autosomal Recessive

Variant(canFam6):
chr27:44456677: C>T

Breed: Miniature Schnauzer
Schnoodle
Standard Schnauzer

General Information: Persistent Müllerian Duct Syndrome (PMDS) is an inherited disorder affecting male dogs, where the Müllerian ducts, precursors to female reproductive organs, fail to regress during fetal development, leading to persistence of these structures alongside normal male anatomy. Approximately half of affected males have normal external genitalia but retain internal female reproductive organs like the uterus, while the other half also exhibit Cryptorchidism, which can cause infertility and increase the risk of testicular tumors. In some cases, affected dogs may have smaller testes, and if the uterus becomes infected, a hysterectomy may be necessary. This syndrome exclusively manifests in males; females with the condition maintain normal internal and external female anatomy.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Unlikely Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing of the AMHR2 gene identifies carriers of persistent Müllerian duct syndrome in dogs, inherited in an autosomal recessive pattern affecting only males. Male dogs require two copies of the mutated gene to develop the disease, while females with two copies do not show symptoms. Carrier dogs generally do not exhibit signs of the disease but breeding two carriers increases the risk of producing affected male pups, who have a 25% chance of inheriting both copies of the mutation. It is crucial to perform genetic testing before breeding to prevent passing on the mutation, and avoiding breeding known carriers together is recommended to eliminate the risk of affected offspring.

References:
Wu X, Wan S, Pujar S, Haskins ME, Schlafer DH, Lee MM, Meyers-Wallen VN. A single base pair mutation encoding a premature stop codon in the MIS type II receptor is responsible for canine persistent Müllerian duct syndrome. J Androl. 2009 30(1):46-56.