Bladder, Urethra and Ureters
The most common causes of hematuria in horses are penile SCC and urolithiasis.
Kidney disorders are rarely treatable in the horse. Luckily, renal failure progresses slowly in the equine and diagnosis of renal disorders may not be imminently fatal. However, diagnosis of kidney disease is often delayed due to the lack of clinical signs prior to the onset of renal failure. Renal hemorrhage (hematuria due to blood coming from the kidneys) is considered idiopathic and usually becomes bilateral with time. It may be due to toxins causing medullary crest necrosis. This disorder is considered not treatable; surgery on the kidneys is rarely performed.
Solitary lesions of the bladder apex can be treated by resection cystoplasty (cut off end of bladder and close). However, neoplasia is usually advanced by the time of diagnosis and cutting off the end of the bladder is usually not sufficient to resolve the problem.
Stallions with urethral hemorrhage present for hemospermia associated with pain on ejaculation. Geldings are presented for hematuria with minimal other clinical signs. On endoscopy, linear urethral defects are found at the level of the ischial arch (near openings for accessory glands). It is theorized that the bleeding is due to “blow out” of the corpus spongiosum penis. Blood is seen at end urination when the bulbospongiosus muscle contracts to expel urine (and there is an increase in pressure in the corpus spongiosum).
Treatment involves prolonged sexual rest and/or temporary perineal urethrostomy. By opening the corpus spongiosum penis, pressure does not build up and bleeding is minimized. Because the CSP is the suspected culprit, the PU may not need to enter the urethral lumen but may just extend through the CSP.
Urethrorrhexis (urethral laceration)
The urethra is relatively superficial in the perineal and inguinal region. Trauma from kicks, barbed wire, and jumping fences can lead to laceration of the urethra. The penis has also been lacerated accidentally in castration procedures. Following trauma, urine leakage leads to a pronounced soft tissue inflammatory reaction with secondary edema of the prepuce, inguinal region and hindlimbs.
Diagnosis may be difficult. Ultrasound and endoscopy can be useful. Fluid aspirated from the tissues will have an ammonia smell, particularly if heated. Dyes and positive contrast radiographs may be needed.
Treatment goals :
- control regional inflammation with NSAIDs, hydrotherapy, antibiotics
- surgical resection of damaged tissue
- divert urine flow (typically by a perineal urethrotomy above the laceration)