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

The study investigates eight cases of adult horses suffering from obstructive nephrolithiasis (kidney stones) and/or ureterolithiasis (ureteral stones), discovered between 1981 and 1987. These conditions were found to be linked with chronic renal failure (long-term, irreversible damage or loss of kidney function). The observations included clinical findings, diagnostic lab results, and postmortem examinations in all affected horses.

Study Subjects and Presentation

• The study focused on eight adult horses, their ages ranging between 2 to 17 years. Notably, five out of eight horses were between the ages of 2 and 3.
• The majority of horses in the study were Thoroughbreds, with just one being a Standardbred.
• The gender distribution was equal with four being female and, in males, two were gelded (castrated).
• Interestingly, only one horse exhibited bilateral ureteral obstruction (blockage in both ureters), while the others presented with unilateral obstruction (blockage in one ureter).
• All subjects were referred for evaluation due to weight loss, poor performance, and/or a decrease in appetite.

Clinical Findings and Diagnosis

• Every horse in the study showed similar bilateral renal pathological findings (abnormalities in both kidneys) pointing to chronic intermittent or complete blockage.
• Diagnosis of obstructive nephrolithiasis and/or ureterolithiasis was confirmed for all hospitalized horses based on rectal examinations and/or ultrasound scans of the kidney.
• Supportive evidence of chronic renal failure was noted in all horses, either via clinical findings, lab results, or post-death examination.

Treatments and Outcome

• Surgery to remove the calculi (stones) was performed on only one horse.
• Although the exact cause, or etiopathogenesis, could not be definitively determined, histopathologic findings (microscopic examination of tissue) in the kidneys of the study subjects suggested that the renal failure could be secondary to the obstructive urinary disease.

This study underscores the importance of a thorough evaluation in horses showing signs of weight loss, poor performance, or decreased appetite, as these symptoms could indicate serious underlying conditions such as obstructive nephrolithiasis, ureterolithiasis, and chronic renal failure.