Fig. 5. Ultrasonographic images of the left ureter (A–C) and right ureter (D–F) from a horse with a bladder stone (not shown) and an obstructive ureterolith (arrow) in the proximal right ureter (F). Note the enlarged size, wall thickening (brackets), and distention along the entire lengths of both ureters in this horse. The distal left and right ureters are shown in the top row, mid-ureters in the middle row and proximal ureters in the bottom row.
Treatment recommendations for horses with a
single cystolith as the primary finding were rela- tively straightforward. Bladder stones are typi- cally removed via perineal urethrostomy inmales or manually through the urethra in females. When- ever possible, stones are removed intact. Multiple techniques to break up stones have been used at the University of California, Davis (UC Davis), includ- ing Knowle’s forceps, radial shock wave lithotripsy, laser lithotripsy, and less often, hammer and chisel fragmentation.12 Most recently, the addition of a laparoscopic specimen retrieval pouch has been used to aid in the removal of cystoliths.13 Nephrolith removal has been attempted in some horses but has
been met with limited success. Removal of ureter- oliths via a standing flank approach has also been described but was not performed in any study cases.14 It should also be mentioned that all cases were evaluated in a systematic manner by one of two highly experienced ultrasonographers (MBW, BV) at an academic institution with a service dedicated to large animal ultrasonography. Over the same 10-year period, 172 scans were performed of the entire urinary tract by the UC Davis Large Animal Ultrasound Service, and this number excludes addi- tional horses presenting for complete abdominal ultrasound examinations. It is recognized that ex-
