The Use of Pneumatic Impact Lithotripsy in a Laparoscopic Retrieval Pouch for Removal of Large Cystoliths in Two Female Horses

Highlights

• Two mares were examined for signs of cytolithiasis.

• Transrectal palpation and cystoscopy revealed a type I cystolith, measuring 10–12 cm.

• Pneumatic impact lithotripsy enabled effective lithotripsy.

• The use of a pouch prevented further mucosal trauma and spreading of calculi debri.

• No complications were encountered when using this technique in two mares.

Abstract

Two mares, aged 15 and 21 years, were examined because of urinary incontinence, intermittent hematuria, and urine scalding. On admission of both horses, physical parameters were within normal limits and urine scalding of the skin at the ventral perineum was noted. Transrectal palpation and cystoscopy revealed a large type I cystolith (>10 cm) with associated hyperemia and focal ulceration of the bladder mucosa. In horse 1, hemogram, serum biochemical analysis, and renal ultrasound were not performed because of owner finances. In horse 2, results from hematological and serum biochemical analysis were unremarkable and renal ultrasonography did not reveal any abnormalities. Pneumatic impact lithotripsy in a laparoscopic retrieval pouch was performed under cystoscopic guidance after caudal epidural anesthesia, with the horses standing and under sedation. A laparoscopic retrieval device was passed alongside a flexible endoscope into the urinary bladder and the cystolith was manipulated into the pouch. A customized single stainless-steel rod scaler attached to an air compressor was used for fragmentation of the cystolith contained within the retrieval pouch. Lithotripsy time was 42 minutes for horse 1 and 31 minutes for horse 2. Both horses were released from hospital the day of surgery. Both horses were continent and voided normal streams of urine for the duration of the follow-up periods of 27 and 19 months for horse 1 and horse 2, respectively. Pneumatic impact lithotripsy in a laparoscopic retrieval pouch provided a time-efficient and minimally invasive surgical treatment option for removal of large cystoliths in mares.

Introduction

Cystolithiasis refers to the presence of one or more calculi in the urinary bladder and is more commonly diagnosed in male than in female horses [1]. Common clinical signs include hematuria exacerbated with exercise, pollakiuria, stranguria, and dysuria. In addition, urine scalding of the hind limbs and perineum may occur in mares because of urinary incontinence [1].

In horses, cystoliths are primarily composed of calcium carbonate and are classified as type I or type II [[1], [2], [3]]. Type I cystoliths account for approximately 90% of the cases, are yellow-green, have a spiculated surface, and have variable resistance to fragmentation [1,3]. Less commonly encountered, type II cystoliths are gray-white with a smooth surface and high resistance to fragmentation. Type II cystoliths typically contain phosphate in addition to calcium carbonate [[1], [2], [3]].

The rough and spiculated surface of type I cystoliths grabs into the mucosa of the urethra and bladder, thus causing trauma and making calculi removal through the urethra difficult. In mares, owing to the urethra being short and distensible, most cystoliths are still retrieved through the urethra [1,3]. However, mares with larger type I cystoliths typically require lithotripsy or sphincterotomy to avoid traumatic tearing of the bladder neck or urethra on calculi retrieval [1,3].

We report the use of pneumatic impact lithotripsy and a retrieval pouch for straightforward and time-efficient removal of large cystoliths (>10 cm) in two mares. A similar technique has been recently described in male horses after standing perineal urethrotomy [4]. To the authors’ knowledge, no reports exist of the use of this technique in female horses.