Case Presentation

An 8-week-old, intact male American pit bull terrier presented for evaluation of abnormal-appearing external genitalia. The dog defecated normally but urinated from an orifice immediately ventral to the anus. Physical examination findings were unremarkable with the exception of the external genitalia. Results of a complete blood count and serum chemistry panel were also unremarkable. An 8-French red rubber catheter was inserted into the orifice ventral to the anus, and urine was aspirated. A band of pink tissue, continuous with the dorsal aspect of the urethra, ended at an abnormally shaped penis with no orifice. Both testicles were palpable and laterally displaced. FIGURE A and FIGURE B show the dog in dorsal recumbency. FIGURE C is a close-up of the perineal region.

1. What are the diagnosis and pathogenesis of this condition?

2. What are the different anatomic locations for this type of defect?

3. What breed is predisposed to this condition?

4. What treatment options are available for this condition?

Answers and Explanations

1. Perineal hypospadias with penile and preputial hypoplasia. Hypospadias results from failure of the urogenital folds to fuse in utero, resulting in incomplete formation of the penile urethra. Penile hypoplasia and an incompletely fused prepuce commonly accompany hypospadias.

2. The external urethral orifice can open anywhere along the length of the urethra, from the normal opening area to the perineal region. Reported locations, moving from cranial to caudal, include glandular, penile, prescrotal, scrotal, and perineal areas.

3. This condition appears to be hereditary in Boston terriers.

4. Treatment depends on the location of the urethral orifice. Mild defects may not require correction. In cranial locations, primary closure of the defect or partial penile amputation can be curative. Reconstruction or cranial advancement of the prepuce may also be required. When the external urethral orifice is located more caudally, partial penile amputation and scrotal or perineal urethrostomy may be indicated. A recent article¹ described a technique for creating a urethral conduit from the preputial remnant in a dog with perineal hypospadias.

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For the dog described in this report, the perineal location of the urethral opening and lack of distal urethra prohibited reconstruction. The hypoplastic penile and preputial remnants were excised, and castration was performed (FIGURE D). The dog recovered uneventfully from surgery and was clinically normal at the time of suture removal.

Surgery was performed on this dog at a young age so the animal could be adopted from a shelter. Because the hypoplastic penile tissue was nonfunctional, surgery could have been performed at a later time. Delaying surgery would likely have been of no consequence, unless the dog began self-mutilating or developed an infection of the abnormal tissue. No further treatment was required in this case, although the perineal location of the urethral opening (FIGURE E) places this dog at lifelong risk for ascending urinary tract infections.

Reference

1. Cashmore RG, Ladlow JF. Creation of a urethral conduit from a preputial indirect flap in a dog with perineal hypospadias. Vet Surg 2010;39:14-20.