Obstructive Urolithiasis in Horse

Abstract

Background: Obstructive urinary tract disease in horses is a rare and low prevalence pathology in the species, but potentially severe. It is an emergency condition that presents variable clinical signs and depends on the anatomical location of the obstruction. The bladder calculus are the most common followed by the urethra and less commonly seen are the kidney or ureteral. The main crystalloid component of uroliths in horses is calcium carbonate. The higher prevalence of urolithiasis in male horses is justified by some anatomical differences between genders. The urethra of males is narrower and longer than that of females. The tissue injury is the most important factor for the development of uroliths in horses. Desquamation of epithelial cells, presence of leukocyte and necrotic cell debris are relevant contributors to crystal growth. Urinary stasis favors nucleation by increasing the chance of contact between crystalloid material and urinary epithelium. Once crystal growth has begun, the urine alkalinity of the equines favors the crystallization and further deposition of other components, especially calcium carbonate. Typical clinical signs of urolithiasis include tenesmus, dysuria, strangury and polaquiuria. Hematuria is often present, mainly observed after exercise and at the end of urination. In addition signs of colic are quite frequent in the acute bladder and urethral urolithiasis due to bladder distension. Upper urinary tract surgery may be technically challenging due to limited structural exposure, especially in adult horses The prognosis for horses with urolithiasis depends on the location of the urolith and the degree of renal injury that occurred.Case: This report aims to describe a rare case of obstructive urolithiasis in a 8-year-old castrated male horse with 24 h evolution. The horse was expressing signs of abdominal pain and during the transretal examination through palpation, it was possible to notice great distension and turgidity of the bladder, in addition to a high pain sensitivity to the palpation of the kidneys. Was perform urethral catheterization, but it was unproductive. The diagnosis was made through perineal ultrasonography and treated surgically by perineal urethrotomy. The animal presented an excellent evolution after being discharged after 10 days of hospitalization and did not present any complication or recurrence of the disease after one year of the procedure.Discussion: Urolithiasis in horses has a prognosis dependent on the location of the urolith and the degree of renal damage. Cases of obstructive urolithiasis in horses are rare and require prompt and appropriate intervention. Therefore, a rapid and accurate diagnosis is directly related to the success of the treatment. In the present case, the animal had characteristic clinical signs of an acute abdomen. Transrectal palpation, for evaluation of the intestinal portions, was important to diagnose an excessively distended urinary vesicle with no intestinal changes. Transcutaneous ultrasonography of the perineum allowed visualization of the calculus, and then a case of perineal urolithiasis was diagnosed. The choice for perineal urethrotomy was performed because of the ease of palpation of the calculus through the skin below the anus and because it is a non-invasive technique. The urethra was sutured to guide the cicatricial process and the urethral catheter was maintained, reducing the risks of occlusion of the urethral lumen.

Obstructive Urethrolithiasis in a Mule

“…Relatively large urethral uroliths that cause obstruction in horses are rare [5]. However, there are reports describing calculi of different sizes [2,12] and weighing up to 803 g [8], causing mild to severe clinical signs according to the degree of obstruction in horses [3,6,11], and donkeys [14,15]. Uroliths obstructing the urethra of male horses may be related to urethral narrowing at the ischial arch [5].…”

“…Local anesthesia included epidural anesthesia with bupivacaine 4 (0.06 mg/kg), and local blockade of the pudendal nerve with 10 mL of 2% lidocaine without vasoconstrictor 5 and 10 mL of bupivacaine 4 . Flunixin meglumine 6 (1.1 mg/kg), ceftiofur 7 (4.4 mg/kg), and 5,000 IU of antitetanic serum 8 were administered preoperatively.…”

“…The pathophysiology of calculi formation in horses is poorly elucidated, but the mechanism behind their formation is believed to be directly linked to increased urine concentration, prolonged urinary retention time, and crystal growth promoters, such as inflammation and nutritional factors [5,6]. Squamous epithelial cells, leukocytes, non-absorbable sutures, and necrotic tissues have been reported as nuclei of cystic calculi, with high salt levels (mainly calcium carbonate), and urine alkalinity as predisposing factors [11].…”

“…Squamous epithelial cells, leukocytes, non-absorbable sutures, and necrotic tissues have been reported as nuclei of cystic calculi, with high salt levels (mainly calcium carbonate), and urine alkalinity as predisposing factors [11]. Such characteristics can lead to solute precipitation, serving as the nucleus for mucoprotein consolidation and calculi formation [3,6].…”

“…In the reviewed literature, there are several case reports of urolithiasis in horses [3,5,6,11] and donkeys [1,10,14,15], but the only mention of this condition in mules occurred as incidental findings at a slaughterhouse [4]. Therefore, this work aims to describe the first report and successful treatment of obstructive urethrolithiasis in a mule (Equus asinus x Equus caballus).…”