Urethral Defects Causing Hematuria in Adult Male Horses

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 can cause a "blowout" tear in the urethral mucosa.

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 can be affected; however, 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 in most cases on the dorsal convex surface of the urethra at the level of the ischial arch (see endoscopic image of urethral defect).

Urethral defect, endoscopic image, horse

Image

Courtesy of Dr. Thomas J. Divers.

• Subischial perineal corpus spongiotomy

Some cases of urethral defect heal spontaneously; however, many continue with intermittent hemorrhage, although anemia is very rare. Breeding rest is recommended for stallions. Subischial perineal urethrotomy or corpus spongiotomy decreases 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.

• Glass KG, Arnold CE, Varner DD, Chaffin MK, Schumacher J. Signalment, clinical features, and outcome for male horses with urethral rents following perineal urethrotomy or corpus spongiotomy: 33 cases (1989-2013). J Am Vet Med Assoc. 2016;249(12):1421-1427.

• Fubini SL, Delco M. Surgery of the equine urinary tract. Vet Clin North Am Equine Pract. 2022;38(1):141-153.

• Also see pet owner content regarding noninfectious diseases of the urinary system in horses.