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Urethral Defects Causing Hematuria in Adult Male Horses


Thomas J. Divers

, DVM, DACVIM, DACVECC, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University

Last full review/revision Jan 2021 | Content last modified Mar 2021
Topic Resources


The cause of urethral defects is not proved, but they are believed to occur because of high pressure in the corpus spongiosum at the end of urination in geldings or during ejaculation in stallions. This high pressure may cause a "blow-out" tear in the urethral mucosa.

Clinical Findings and Diagnosis

  • Diagnosis based on clinical signs and urethral endoscopy

The clinical signs of urethral defects are limited to hematuria at the end of urination, associated with contractions of the bulbourethral muscle in geldings or with hemospermia and decreased fertility in stallions. All breeds may be affected, although the disorder seems more common in Quarter horses.

Diagnosis of a urethral defect is based on clinical signs and urethral endoscopic findings. The urethral defect is seen in most cases on the dorsal convex surface of the urethra at the level of the ischial arch.


  • Urethrotomy or other surgery to reduce urethral pressure and allow defect to heal

Some cases of urethral defect may heal spontaneously, but most continue with intermittent hemorrhage, although anemia is very rare. Breeding rest is recommended for stallions. Subischial perineal urethrotomy or corpus spongiotomy reduces vascular pressure in the corpus spongiosum during urination and ejaculation, allowing the defect to heal. A buccal mucosal graft and topical cautery have also been used to repair the defect.

Key Points

  • Bleeding at the end of urination or during ejaculation in adult male horses with no other clinical abnormalities is characteristic of a urethral tear.

  • Diagnosis is often made by urethral endoscopy.

  • Treatment may be required for breeding stallions if fertility is reduced.

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