Persistent Müllerian Duct Syndrome
Persistent Müllerian Duct Syndrome (PMDS) is a reproductive disorder in which the uterus and other parts of the female reproductive tract develop in male dogs. An important consequence of this disease is cryptorchidism (undescended testicles), which occurs in ~50% of affected dogs and causes infertility, as well as increased risk for testicular tumors. The external genitalia can be otherwise normal, making it easy to overlook PMDS as the underlying cause of cryptorchidism. Female dogs are not affected by this disease.
Note: Cryptorchidism has many potential causes, of which PMDS is only one.
Breeds reported to have Persistent Müllerian Duct Syndrome
The genetic mutation that causes PMDS has been reported in Miniature Schnauzer dogs, and the test that we offer specifically checks for this mutation. Based on preliminary data, we believe that the mutation is relatively common in this breed. Mutation screening has not been reported in other breeds. However, PMDS has been described in the Papillon, Belgian Malinois, Leonberger, Doberman Pinscher, Basset Hound, and English Cocker Spaniel. It is unknown if these breeds have the same mutation that causes the disorder in Miniature Schnauzers or if there are distinct mutations present.
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;30:46-56.