Objective - To describe a technique for endoscope-assisted disruption and removal of urinary calculi using a holmium:YAG laser in sedated, standing horses. Study Design - Retrospective study. Animals - Six horses with urinary calculi. Methods - A holmium:YAG laser was used to disrupt naturally occurring urinary calculi in horses (4 geldings, 1 stallion, 1 mare). Ischial urethrotomy was performed in male horses to provide a portal for the endoscope and laser fiber. Calculus fragments were removed by a combination of lavage, transendoscopic basket snare removal, forceps, and digital manipulation. Ischial urethrotomies healed by second intention. Follow-up was obtained by recheck examination and telephone interview of owners. Results - No major operative or postoperative complications occurred. Two calculi (1 stallion and 1 mare) were fragmented by a combination of laser ablation and manual disruption with a lithotrite. Postoperative dysuria occurred in the mare, but resolved after 1 month. Mean (± SD) follow-up was 306 ± 149 days; no other complications were reported. Conclusions - Calcium carbonate urinary calculi (up to 15 cm in diameter) in horses can be effectively fragmented with a holmium:YAG laser. It is not known if this technique would be completely effective for larger calculi or extremely dense calculi. Clinical Relevance - Calculus disruption by an endoscopically assisted holmium:YAG laser offers a minimally invasive method that can be performed in standing horses and that minimizes patient risk.
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