Abstract

Background:
Obstructive urolithiasis is an important urinary tract disorder in male small ruminants and is usually recognized as lower urinary tract obstruction. Upper urinary tract involvement may be overlooked when gastrointestinal or systemic signs predominate.

Case Description:
A three-year-two-month-old Corriedale wether sheep was presented with anorexia, lethargy, foul-smelling diarrhea, and pale mucous membranes. Parasitic enteritis was initially suspected. Hematology and serum biochemistry revealed marked azotemia, hypermagnesemia, hypocalcemia, hypochloremia, and an increased anion gap. Despite supportive treatment, the sheep deteriorated and was euthanized for animal welfare reasons. Gross necropsy revealed right hydronephrosis, a calculus obstructing the right ureter, ureteral mucosal ulceration, bilateral renal pelvic hemorrhage, small uroliths and urinary sediment in the urinary bladder, and bladder mucosal petechiae. No urinary bladder rupture was observed. Infrared spectrophotometric analysis identified calcium carbonate as the predominant component of the right ureteral calculus.

Conclusion:
Calcium carbonate urolithiasis in adult wether sheep may involve the ureter and contribute to severe renal dysfunction without typical signs of distal urethral obstruction. Urolithiasis should be considered in adult sheep with nonspecific systemic deterioration, especially when urination cannot be confirmed.

Key words: Azotemia; Calcium carbonate; Sheep; Ureteral obstruction; Urolithiasis.