Persistent Müllerian Duct Syndrome

Persistent Müllerian duct syndrome is a pathology that affects the normal development of the reproductive system in males and can cause infertility.

Symptoms

Both males affected by the syndrome and carriers appear externally normal, although approximately 50% of affected dogs are cryptorchid (one or both testes have not descended into the scrotal sac during the development of the reproductive tract). Males with cryptorchidism have an increased risk of Sertoli cell tumors and an increased risk of urinary tract infections and inguinal hernias.

Disease Management

Treatment of dogs affected by Müllerian duct syndrome includes castration to prevent the development of related diseases such as urinary tract infections or tumors. In some cases, surgery may be necessary to remove abnormal reproductive system structures. The prognosis is usually good with appropriate treatment.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

During the development of the male reproductive system, the Müllerian inhibitory substance, also known as antimüllerian hormone, is critical for the development of the reproductive system. In addition to having male internal genitalia, males with Müllerian duct syndrome have two oviducts, a complete uterus, a cervix and part of the vagina, which ends in the dorsal prostate. The cryptorchid testes of affected dogs lack germ cells, although the scrotal testes appear normal. This syndrome is quite common in dogs of the miniature Schnauzer breed, it has been shown that it may be due to the presence of two copies of the c.262C>T variant of the AMHR2 gene encoding for the antimüllerian hormone receptor.

Most affected breeds

Basset Hound
Miniature Schnauzer

Bibliography

Wu X, Wan S, Pujar S,et al. 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 Jan-Feb;30(1):46-56.