Persistent Müllerian duct syndrome
Persistent Müllerian duct syndrome is an autosomal-recessive genetic disease of dogs characterized by ambiguous gonadal and sex differentiation. It is a rare form of male pseudohermaphroditism where Müllerian duct derivatives are retained in otherwise normal male dogs.
Both male and female dogs can be carriers.
During sexual differentiation of male embryos, the Müllerian ducts fail to regress in males during sexual differentiation as a result of abnormalities in the synthesis or action of anti-Müllerian hormone. Müllerian Inhibiting Substance (anti-Müllerian hormone), plays an important role in mediating regression of the Müllerian ducts, the embryologic precursors of the uterus, Fallopian tubes, and upper vagina. The causes retained rudimentary Müllerian structures or an infantile uterus and Fallopian tubes.
A breed predisposition has been noted in the Miniature Schnauzer and Bassett Hound. Affected miniature schnauzers are 78,XY males and have bilateral testes and normal androgen-dependent masculinization of the internal and external genitalia. However, all Müllerian duct derivatives, bilateral oviducts, a complete uterus with cervix and the cranial portion of the vagina, are also present.
In dogs, this condition is frequently associated with cryptorchidism (approximately 50% of affected dogs have normally descended testes and are fertile), hypospadias and prostate disease (e.g. deformed or absent prostate).
Affected dogs have normal development of external genitalia, but internally develop fully differentiated Müllerian and Wolffian duct systems.
Most dogs are diagnosed at time of routine neutering and a differential diagnosis would include XX sex reversal.
A DNA test is available for detection of this disorder in dogs.
Treatment involves orchidectomy and hysterectomy.
Prevention is limited to the elimination of affected dogs and carriers from the breeding population.
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