Obstructive nephrolithiasis and ureterolithiasis associated with chronic renal failure in horses: eight cases (1981-1987).

Eight adult horses with obstructive nephrolithiasis and/or ureterolithiasis were examined between 1981 and 1987. One horse had bilateral ureteral obstruction at hospital admission; the others had unilateral ureteral obstruction. All horses had similar bilateral renal pathologic findings that were compatible with chronic intermittent or complete obstruction. Horses were referred for evaluation of weight loss, poor performance, and/or decreased appetite. Clinical findings, laboratory results, and/or postmortem findings in all horses supported the diagnosis of chronic renal failure. Age of the 8 horses varied between 2 and 17 years; 5 of the 8 were between 2 and 3 years old. Seven horses were Thoroughbreds and 1 was a Standardbred. Of the horses examined, 4 were females and 4 were males (2 geldings). Diagnosis of obstructive nephrolithiasis and/or ureterolithiasis was made in all of the hospitalized horses based on examination per rectum and/or renal ultrasonographic findings. Surgical removal of the obstructing calculi was performed in one horse. Although etiopathogenesis could not be proven, histopathologic findings in the kidneys of the horses of our study were suggestive of renal failure secondary to obstructive urinary disease.