Penile hypoplasia and rudimentary prepuce in a dog (78,XY; SRY-positive): a case report

This is the first report in the literature concerning penile hypoplasia and rudimentary prepuce in a 78,XY; SRY-positive male that received a successful surgical treatment. A six-month-old male mixed-breed dog with body weight of 3.5 kg and with symptoms of prolonged stranguria and abnormalities of the external genitalia were presented by the owner at the University Surgical Clinic. Clinical, biochemical, radiological, pathological, and genetic examinations of the dog were carried out. Penile hypoplasia and rudimentary prepuce were diagnosed. Early diagnosis of penile hypoplasia and rudimentary prepuce in small animals requires a high level of vigilance and is based on clinical and ultrasonographical findings. The radiography revealed a fan-shaped widening of the caudal part and shortening of the os penis. A hyperechogenic os penis with a wide posterior part and a slightly curved, smooth anterior end was imaged. No normal prepuce structures were observed. The endocrinological examination showed a substantially decreased testosterone level. Fast surgical intervention is preferable and confirms the diagnosis. In the presented case report enlargement of the preputial orifice was applied in order to prevent urinary retention and recurrent urinary tract infections. Orchiectomy was also performed. After the surgery, immediate clinical improvement was noted. The testicular atrophy diagnosed in the histological analysis explains the low level of the hormone. The cytogenetic analysis revealed a normal male set of chromosomes – 78,XY. The molecular analysis showed presence of the SRY gene as well as the ZFY gene, which reside on the Y chromosome and the ZFX, which is X-linked. The successful amplification of the SRY, ZFX, and ZFY genes confirmed the presence of both X and Y chromosomes. Sequencing and comparison with the reference sequence of the canine SRY gene indicated a normal sequence in the examined dog. Given the absence of polymorphisms and mutations in the coding sequence of the SRY gene, it can be assumed that it is not associated with the observed phenotype. The studied case was classified as testicular XY (SRY-positive) disorder of sex development (DSD), the aetiology of which remains unknown.