Research Update: Spontaneous retrograde movement of ureteroliths

In this case series, ureterolith movements in two dogs and five cats were evaluated. Spontaneous retrograde movement of one or more ureteroliths was documented by using radiography, ultrasonography, fluoroscopy, or a combination of ultrasonography and fluoroscopy. These seven cases were obtained from medical records from a 10-year period in which 115 dogs and cats were treated for nephroliths and ureteroliths at a university veterinary hospital.

Retrograde ureterolith movement of about 2 cm was recorded in both dogs and four cats; in one cat, a ureterolith moved 4 cm back into the renal pelvis. In both dogs and one cat, uroliths in the renal pelvis passed into the ureter and then moved retrograde into the renal pelvis. These animals had a markedly increased serum creatinine concentration while the urolith was in the ureter and a decreased serum creatinine concentration after retrograde movement of the urolith into the renal pelvis.

The authors noted that serial monitoring of ureteroliths with diagnostic imaging and routine laboratory testing and treatment with diuretics and intravenous fluids are recommended in uncomplicated cases. Surgery or shockwave lithotripsy is recommended for animals with worsening azotemia or evidence of complete obstruction or infection. The exact mechanism for retrograde ureterolith movement remains unclear.

The authors also noted that in another recent report of 153 cases of ureteroliths in cats, 52 cats were treated by using medical management alone and serial radiographs were monitored in 14 of those cases. Ureteroliths passed spontaneously into the bladder in nine of the 14 cats. In 17 of the 52 cats, medical management was unsuccessful, and these cats were euthanized or died within a month.1

COMMENTARY

This review of seven cases of mobile ureteroliths highlights a potential difficulty in treating ureteroliths in small animals. Clinical monitoring by using imaging studies, serum chemistry profiles, and urinalyses is critical in determining if surgical or medical management is warranted. Clinicians should be aware that the ureteroliths may move retrograde into the renal pelvis or spontaneously pass into the urinary bladder. Azotemia may improve or resolve in either instance. Furthermore, intraoperative identification of mobile uroliths may be challenging and may affect the location of the incision: renal pelvis or ureter. The authors present useful guidelines for clinicians: early surgical intervention for nonmobile, obstructive, or infectious ureteral lesions and surgery or lithotripsy for nephroliths secondary to retrograde movement.

Dalby AM, Adams LG, Salisbury SK, et al. Spontaneous retrograde movement of ureteroliths in two dogs and five cats. J Am Vet Med Assoc 2006;229:1118-1121.

REFERENCE

1. Kyles AE, Hardie EM, Wooden BG, et al. Management and outcome of cats with ureteral calculi: 153 cases (1984-2002). J Am Vet Med Assoc 2005;226:937-944.

The information in "Research Updates" was provided by Veterinary Medicine Editorial Advisory Board member Joseph Harari, MS, DVM, DACVS, Veterinary Surgical Specialists, 21 E. Mission Ave., Spokane, WA 99202.

Joseph Harari, MS, DVM, DACVS