Obstructive urolithiasis in ruminants: Medical treatment and urethral surgery

Urinary tract obstruction in ruminants is usually caused by calculi becoming lodged in the urethra of intact and castrated males. The distal aspect of the sigmoid flexure and the urethral process are the most common sites of obstruction in cattle and sheep, respectively. Small ruminants and feedlot steers typically have multiple calculi, whereas steers and bulls on range typically have one large calculus. Rupture of the urethra or urinary bladder commonly results. Many options for surgical treatment exist. The selection of a procedure should be based on the animal's intended use, the expense, the available facilities, the practitioner's surgical experience, and the animal's condition. Surgery of the urethra can be performed in the field, and most procedures can be accomplished quickly and inexpensively. However, these procedures are best suited for salvage of animals intended for slaughter, as recurrent obstruction and stricture of the urethra may occur after surgery and some of these procedures eliminate the animal's ability to breed.