Urolithiasis remains an infrequently diagnosed condition in horses, constituting 0.11% of equine admissions to university veterinary teaching hospitals in the United States over a 19-year period.1 Of these reported cases of urolithiasis, 59.7% involved cystic calculi. Cystic calculi are more common in geldings and stallions than in female horses,1–3 and this difference is believed to be attributable to the longer, narrower urethra in males versus females.4
The most common clinical sign associated with cystic calculi in horses is hematuria, which is often exacerbated by exercise.3 Additional clinical signs include tenesmus, incontinence, dysuria, stranguria, pollakiuria, urine scald, and, less commonly, weight loss.1–3,5,6
Uroliths in horses are primarily composed of calcium carbonate crystals, with a smaller proportion of calculi containing magnesium ammonium phosphate, calcium oxalate, and calcium sulfate in addition to calcium carbonate.1,3,4,6,7 Uroliths can also be classified as either type 1 or type 2, with type 1 accounting for approximately 90% of uroliths in horses.3 Type 1 calculi are comprised of calcium carbonate, typically have a spiculated surface with a yellow to yellow-green color, and are relatively easily fragmented. In contrast, type 2 uroliths contain phosphate in addition to calcium carbonate, have a relatively smooth surface with a grayish-white color, and are more resistant to fragmentation.
A diagnosis of cystic calculi is typically made on the basis of clinical signs and results of palpation per rectum, transrectal ultrasonography, and transurethral endoscopic examination of the urinary bladder.1–6,8,9 Transurethral digital palpation and direct visualization of a cystic calculus in a mare have also been reported.9
Several methods have been described for the removal of cystic calculi from horses, including laparocystotomy,1–3,5,10 laparoscopic techniques,11–13 transurethral removal,1,4,14 pararectal cystotomy,5,15 and removal through a perineal urethrotomy (males only).1,5,6,8,9 Currently, laparocystotomy is considered the treatment of choice,1–3,5,6,10 given that it allows for complete removal of larger calculi, minimizes trauma to the urinary bladder and urethra, and avoids the difficulties often encountered during removal from standing horses.
Techniques reported to facilitate removal of cystic calculi from standing sedated horses, either by a transurethral approach or through a temporary perineal urethrotomy site, include manual crushing,1,2 fragmentation with a mallet and osteotome,5 pulsed-dye laser,16,17 holmium:yttrium-aluminum-garnet laser,9,18 electrohydraulic shockwave,4 or ballistic shockwave,19 followed by fragment removal. Because of the shorter length, larger diameter, and distensible nature of the urethra in mares, large calculi can be removed intact, in conjunction with urethral sphincterotomy when necessary.1,2,5,14
Intraoperative complications associated with removal of cystic calculi from standing horses include rectal tear,1 perforation of the urinary bladder or urethra,1,4 unsuccessful attempts to fragment calculi,16 and an inability to remove all fragments from the bladder.1,6,11 Reported postoperative complications include peritonitis, fever and urethritis,1 cystitis,1,4 retained fragments causing urethral obstruction,4 urethral stricture,2 and recurrence related to retained fragments serving as a nidus for future calculus formation.1,11 Up to 41% of cystic calculi reportedly recur following removal, regardless of the method used for removal, and 47% are reported to recur when retrieved through perineal urethrotomy.1
A recent case report8 described removal of small cystic calculi from 2 geldings through a perineal urethrotomy site, without fragmentation, with the aid of a laparoscopic retrieval device. The authors concluded that although the technique was successful for removal of smaller calculi from standing sedated horses, larger calculi that cannot be removed by this method should be treated by other previously described techniques. We hypothesized that a laparoscopic specimen retrieval pouch could be effectively used to contain and stabilize cystic calculi requiring fragmentation to facilitate removal from standing horses. We also hypothesized that the pouch would protect the urinary bladder and urethra from iatrogenic trauma during removal of intact calculi or following fragmentation of calculi that could not be removed intact.
Materials and Methods
Case selection
Medical records of horses brought to the William R. Pritchard Veterinary Medical Teaching Hospital of the University of California-Davis from February 2012 to April 2015 were reviewed to identify those with a diagnosis of cystic calculus that had subsequently undergone calculus removal by use of a laparoscopic specimen retrieval pouch while standing.
Medical records review
Information obtained from the medical records included horse signalment; problem that prompted the hospital visit; clinical signs; results of physical examination and ultrasonographic and endoscopic imaging; abnormalities identified through preoperative CBC, serum biochemical analysis, and urinalysis; duration of surgery and technique used; intra- and postoperative complications; and duration of hospitalization.
Surgical procedure
Aseptic technique was used to insert a 14-gauge, 5.25-inch catheter into the right jugular vein of each horse. In preparation for calculus removal, horses were given penicillin G procaine (22,000 U/kg [10,000 mg/lb], IM), gentamicin sulfate (6.6 mg/kg [3.0 mg/lb], IV), and flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV), and tetanus toxoid was administered. Horses were then restrained in standing stocks, and a loading dose of detomidine hydrochloride (0.01 to 0.02 mg/kg [0.0045 to 0.009 mg/lb]) was administered IV. Sedation was maintained with a continuous IV infusion of detomidine (0.02 to 0.05 mg/kg/h [0.009 to 0.023 mg/lb/h]). Caudal epidural anesthesia was provided with 2% lidocaine hydrochloride solution (0.2 mg/kg [0.09 mg/lb]). In 1 horse, an epidural cathetera was placed in anticipation of the need for repeated epidural delivery of local anesthetic solution in the days following calculus removal because additional endoscopic procedures involving laser lithotripsy were planned to address concurrent nephrolithiasis. Adjunctive sedatives and analgesics were administered as needed during calculus removal, at the discretion of the attending anesthesiologist. This included IV administration of morphine sulfate (0.1 mg/kg [0.045 mg/lb]) to 5 horses during manipulations to facilitate calculus removal and IV administration of a bolus of acepromazine maleate (0.04 mg/kg [0.02 mg/lb]) to 1 horse after fractious behavior was observed when it was placed in the standing stocks.
The rectum of each horse was evacuated of feces, and the perineum was aseptically prepared for surgery. For geldings, 2% lidocaine solution was injected SC at the planned site of perineal skin incision to ensure complete desensitization of the area because caudal epidural anesthesia in these horses was deemed to have been only partially effective on the basis of signs of diminished, but not absent, skin sensation. A flexible urinary catheterb was placed in the urethra, and a standard perineal urethrotomy20 was performed to gain access to the urinary bladder. Briefly, an approximately 8-cm longitudinal midline skin incision was made in the perineum, beginning 5 cm distal to the anus and extending ventrally to the level of the ischial arch. Dissection was directed through the subcutaneous tissues, and in geldings, the paired retractor penis muscles and bulbospongiosus muscle were sharply divided. The incision was continued through the corpus spongiosum penis in geldings to expose the caudal aspect of the urethra, and a longitudinal incision was made directly over the indwelling urinary catheter into the urethral lumen. A flexible videoendoscopec with a 1.1-m working length and 8.2-mm diameter was directed through the perineal urethrotomy site in geldings or was transurethrally directed in mares to allow visualization of the urinary bladder. Insufflation was used as needed, and urine was intermittently drained from the urinary bladder with a 28F Foley catheter to improve visibility.
The urinary bladder was examined, the calculus was observed, the 15-mm-diameter laparoscopic specimen retrieval pouchd was introduced alongside the endoscope, and the pouch was deployed. In each horse, the calculus was manipulated into the pouch, the pouch was closed by placing traction on the purse string attached to the bag, and the introducer was discarded. Following containment of the calculus, each horse received N-butylscopolammonium bromide (0.3 mg/kg [0.14 mg/lb], IV) once, prior to attempts at extraction. Sterile lubricating jellye with 2% lidocaine solution was infused into the urinary bladder by use of a 60-mL syringe and mare insemination pipette, and traction was placed on the purse string to exteriorize the mouth of the pouch.
Once partial exteriorization was achieved, attempts were made to remove the calculus intact by placing traction on the pouch. For 1 mare, the mucosa and submucosa overlying the urethral sphincter were incised to allow for passage of the intact calculus, as previously described.1 For horses in which attempts at intact calculus removal were unsuccessful, pneumatic radial shockwave lithotripsyf (4 geldings; 5 calculi) or manual calculus crushing with Knowles uterine forcepsg (1 mare; 1 calculus) was performed with direct visualization, and the calculi were retained within the pouch. Caudal traction placed on the edges of the pouch by an assistant stabilized the calculus at the trigone of the urinary bladder and contained all fragments within the pouch (Figure 1). During disruption of the calculus, the contents of the pouch were periodically lavaged with warm water through a nasogastric tube to remove fragments and improve visibility. Additional lubricant with 2% lidocaine hydrochloride solution was infused into the urinary bladder as previously described, prior to additional manipulations of the calculus within the pouch.
Photograph of a horse undergoing surgery for removal of a cystic calculus, in which caudal traction is being placed on the opening of a laparoscopic specimen retrieval pouch to stabilize the calculus for fragmentation and subsequent removal.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a horse undergoing surgery for removal of a cystic calculus, in which caudal traction is being placed on the opening of a laparoscopic specimen retrieval pouch to stabilize the calculus for fragmentation and subsequent removal.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a horse undergoing surgery for removal of a cystic calculus, in which caudal traction is being placed on the opening of a laparoscopic specimen retrieval pouch to stabilize the calculus for fragmentation and subsequent removal.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Lithotripsy was continued until the calculus was reduced in size to a point that it could be easily and atraumatically removed from the urinary bladder within the retrieval pouch. Following calculus removal, the endoscope was reinserted into the urinary bladder to visually assess whether trauma had occurred to the urinary bladder and urethral mucosa and to ensure no additional calculi or fragments remained. The pouch was examined for evidence of damage. At the completion of the procedure, the urinary bladder was copiously lavaged with physiologic saline (0.9% NaCl) solution. All surgical incisions were allowed to heal by second intention.
Postoperative care
While hospitalized, horses were monitored for an increase in heart or respiratory rate, fever, and signs of abdominal discomfort and depression, lethargy, anorexia, and laminitis. Additionally, horses were monitored for abnormalities associated with micturition or healing of surgical incisions. Oral administration of antimicrobials and NSAIDs was continued for 7 to 14 days, depending on surgeon preference. Recommendations to discontinue feeding alfalfa hay and to add table salt to the diet were made as a strategy to minimize the likelihood of calculus recurrence.
Outcome
One investigator (SAK) obtained follow-up information from owners or referring veterinarians via telephone by use of a questionnaire.
Statistical analysis
Summary data were calculated to characterize the horses, their calculi, the surgical procedure, and outcomes. Values of continuous data such as age, calculus size, or duration of surgery are reported as mean ± SD.
Results
Animals
Eight horses (5 geldings and 3 mares) met the inclusion criteria for the study. Horses ranged in age from 10 to 24 years (mean ± SD, 17.7 ± 4.8 years). Breeds included Thoroughbred (n = 2), warmblood (2), Quarter Horse (2), Arabian (1), and polo pony (1). Problems that prompted the hospital visit included hematuria after exercise (3 geldings and 3 mares), signs of abdominal discomfort (1 gelding), and pollakiuria (1 gelding). One gelding had a prior history of cystic calculi, which had been removed 9 years earlier by perineal urethrotomy. All horses received full physical, ultrasonographic urinary tract, and cystoscopic examinations.
Ultrasonographic examination of the urinary tract included transcutaneous examination of the left and right kidneys, followed by transrectal examination of the urinary bladder, left kidney, and left and right ureters.21 This examination revealed a bright hyperechoic structure in the urinary bladder of all horses that casted a strong acoustic shadow consistent with cystic calculus. Seven horses had ultrasonographic evidence of concurrent nephrolithiasis (3 in the right kidney, 2 in the left kidney, and 2 in both kidneys). Cystoscopic examination confirmed the presence of a solitary spiculated yellow-green calculus in 7 horses and 2 smooth gray calculi in 1 gelding. Varying degrees of mucosal hyperemia and petechiation indicative of mild to moderate cystitis were detected in 7 horses. Multifocal areas of hyperemia, petechiation, and extensive mucosal ulceration indicative of severe cystitis were identified in the gelding with multiple calculi.
Calculi ranged in diameter from 4.6 to 7 cm (mean, 6.0 ± 0.9 cm). All horses had a preoperative CBC and serum biochemical analysis performed. For 1 horse, abnormalities suggestive of chronic renal insufficiency were identified (BUN concentration, 30 mg/dL [reference range, 12 to 27 mg/dL]; serum creatinine concentration, 2.4 mg/dL [reference range, 0.9 to 2.0 mg/dL]). Results of hematologic evaluation were unremarkable for the other 7 horses. Four horses had a preoperative urinalysis performed before surgery, and positive results of bacterial culture for 1 horse were the only remarkable abnormality identified.
Surgical procedure
For 3 horses (1 gelding and 2 mares), it was possible to remove the calculus intact (Figure 2), although 1 mare required incision of the mucosa and submucosa overlying the urethral sphincter to facilitate calculus removal. For the other 5 horses, fragmentation of the calculus was required to facilitate removal (Figure 3). This was achieved by pneumatic radial shockwave lithotripsy (n = 4) or manual crushing (1). Each laparoscopic retrieval pouch was examined for damage following calculus extraction, with none noted regardless of manipulations or removal method used.
Photograph of a laparoscopic specimen retrieval pouch introducer and detached polyurethane specimen retrieval pouch displaying a cystic calculus successfully removed intact from a horse. Notice the depth of the pouch, which allows for exteriorization of its opening following containment of cystic calculi and facilitates manipulation, stabilization, and, when necessary, fragmentation of calculi. Knowles uterine forceps, not needed for this particular horse, are shown adjacent to the pouch.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a laparoscopic specimen retrieval pouch introducer and detached polyurethane specimen retrieval pouch displaying a cystic calculus successfully removed intact from a horse. Notice the depth of the pouch, which allows for exteriorization of its opening following containment of cystic calculi and facilitates manipulation, stabilization, and, when necessary, fragmentation of calculi. Knowles uterine forceps, not needed for this particular horse, are shown adjacent to the pouch.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a laparoscopic specimen retrieval pouch introducer and detached polyurethane specimen retrieval pouch displaying a cystic calculus successfully removed intact from a horse. Notice the depth of the pouch, which allows for exteriorization of its opening following containment of cystic calculi and facilitates manipulation, stabilization, and, when necessary, fragmentation of calculi. Knowles uterine forceps, not needed for this particular horse, are shown adjacent to the pouch.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a fragmented calculus retrieved from a horse within a laparoscopic specimen retrieval pouch following disruption of the calculus by means of pneumatic radial shockwave lithotripsy.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a fragmented calculus retrieved from a horse within a laparoscopic specimen retrieval pouch following disruption of the calculus by means of pneumatic radial shockwave lithotripsy.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Photograph of a fragmented calculus retrieved from a horse within a laparoscopic specimen retrieval pouch following disruption of the calculus by means of pneumatic radial shockwave lithotripsy.
Citation: Journal of the American Veterinary Medical Association 249, 3; 10.2460/javma.249.3.304
Duration of surgery ranged from 40 to 255 minutes (mean, 125 ± 63 minutes). Duration of hospitalization was 2 days for 3 horses, 4 days for 2 horses, 7 days for 1 horse, 17 days for 1 horse, and 23 days for 1 horse.
Cystic calculi
Crystallographic analysis was performed on 3 calculi from 2 horses to determine their composition. Calculi from both horses were composed solely of calcium carbonate. One of these calculi had the classic yellow-green spiculated appearance typical of a type 1 urolith and was rapidly fragmented. The remaining 2 calculi had the gross appearance of type 2 calculi. Both were smooth, gray in color, and substantially more resistant to fragmentation, which resulted in a longer duration of surgery for the affected horse.
Outcome
Calculi were removed completely from all horses without any fragments remaining in the urinary bladder. Mild hyperemia and submucosal petechiation of the bladder mucosa, similar in severity to initial examination, were the only abnormalities identified by means of cystoscopy in 7 of 8 horses after surgery. For the remaining horse in which a diagnosis of severe cystitis had been made at hospital admission, no difference was identified between results of pre- and postoperative cystoscopic examinations.
Mild hemorrhage was observed during perineal urethrotomy in 1 gelding, but this was easily controlled by isolation and ligation of the bleeding vessel. Postoperative complications were not encountered for any horses, regardless of the technique used to facilitate calculus removal. Follow-up telephone conversations with owners and referring veterinarians revealed that all horses had resumed their typical activity with no recurrence of clinical signs.
Discussion
The laparoscopic specimen retrieval pouch device used to remove cystic calculi from the horses of the present report consists of a 15-mm-diameter, 34.5-cm-long introducer and a 12.7-cm-diameter, 22.9-cm-deep polyurethane pouch. The pouch is attached to a flexible metal ring, which maintains it in an open position without the aid of additional instruments. When the pouch is deployed, a working length of 47.2 cm is achieved. The long working length, coupled with the diameter and depth of the pouch, allows for easy manipulation of large cystic calculi into the pouch.
Pulling on the purse string closes the pouch and detaches it from the metal ring. Because of the depth of the pouch, its opening can be exteriorized through a perineal urethrotomy site in geldings or transurethrally in mares by placing traction on the purse string. In situations in which fragmentation of the calculus was necessary for the horses of the present report, caudal traction on the opening of the pouch allowed for direct visualization of the calculus, provided adequate stabilization necessary to facilitate fragmentation, and obviated the risk of rectal tear, urinary bladder or urethral perforation, or incomplete removal associated with other previously described methods for removal of cystic calculi from standing horses.
Although pneumatic radial shockwave lithotripsy and manual crushing were performed to disrupt calculi in the horses of the present report, several types of lithotripsy have been described to facilitate removal of cystic calculi. Methods include fracturing calculi into smaller pieces by use of a mallet and osteotome,5 electrohydraulic4 or ballistic19 shockwave lithotripsy, and pulsed-dye16,17 or holmium: yttrium-aluminum-garnet9,18 laser lithotripsy. These techniques can be used for standing sedated horses, eliminating the need for general anesthesia, but are often associated with a high incidence of intra- and postoperative complications. Reported complications include, but are not limited to, incomplete calculus removal,1,6,11 rectal tear,1 urinary bladder or urethral rupture,1,4 urethral obstruction,4 and high calculus recurrence rates.1 Because containment and stabilization of cystic calculi were consistently achieved with the laparoscopic retrieval pouch used for the horses of the present report and complications associated with this technique were minimal, its use might also be advantageous in conjunction with other previously described methods of lithotripsy.
Because of the spiculated surface of most type 1 uroliths and manipulations necessary to facilitate removal of uroliths regardless of their composition or gross appearance, severe trauma to the urinary bladder, urethra, or both can be an unavoidable consequence of removal from standing horses through a perineal urethrotomy site (males) or transurethral approach (females). For horses of the present report, postoperative cystoscopy was performed to confirm complete calculus removal as well as to detect any trauma to the urinary bladder and urethra that may have occurred during calculus manipulation. Mild submucosal hyperemia and petechiation were the only sequelae observed following calculus removal by the technique described here. The protection that the laparoscopic retrieval pouch affords the urinary bladder and urethra as calculi are manipulated or fragmented within the pouch and subsequently removed through the urethra while contained within the pouch cannot be overstated. This is considered one of the major benefits associated with this technique.
For 7 of 8 horses of the present report, duration of surgery was comparable to that for other reported methods of cystic calculus removal from standing horses. For the gelding from which 2 smooth gray calculi were removed by use of this technique, the duration of surgery was substantially longer (255 minutes) than that for the other 7 horses. This was in part due to added manipulations necessary to mobilize both calculi into the pouch simultaneously, and because these cystoliths were more resistant to fragmentation, the amount of time necessary to disrupt them prolonged the surgery. For this horse, fragmentation was achieved with pneumatic radial shockwave lithotripsy and was not any more technically demanding than in the other 3 horses that had calculi disrupted with this method. However, the resistance to fragmentation encountered when this method was applied to these calculi resulted in a much more time-consuming process.
As expected, similarities between the horses of the present report and the 2 horses in a previous case report8 were evident. These included easy manipulation of calculi into the retrieval pouch, minimal trauma to the urinary bladder and urethra, complete removal of calculi without debris remaining in the bladder, and a lack of intra- or postoperative complications. We demonstrated that by placing caudal traction on the exteriorized portion of the pouch, stabilization and containment of calculi requiring fragmentation prior to removal were easily achieved and obviated the need for stabilization of cystic calculi per rectum, which had been suggested for removal of large calculi (> 5 cm) in the case report.8 These findings suggested that this technique may be superior to previously described methods for removal of large cystic calculi.
Although laparocystotomy is considered the treatment of choice for removal of cystic calculi,1–3,5,6,10 disadvantages include the need for general anesthesia, difficulty maintaining the urinary bladder in an exteriorized position, risk of incisional infection and dehiscence, and greater cost and longer postoperative convalescence time than that for removal from standing horses. Laparoscopic techniques for removal of cystic calculi from standing sedated or anesthetized horses have been described,11–13 but the need for specialized equipment and advanced training to perform these procedures make them impractical in many circumstances.
Interestingly, 7 horses in the present report had ultrasonographic evidence of concurrent nephrolithiasis. This appeared to be indicative of a higher prevalence of concurrent urolithiasis in other areas of the urinary tract than previously reported for horses with cystic calculi1 and warrants further investigation. Additionally, one horse had evidence of chronic renal insufficiency on preoperative hematologic evaluation, and another had positive results of bacterial culture on preoperative urinalysis. These findings emphasized the need for a thorough preoperative evaluation prior to treatment of cystic calculi, given that additional abnormalities of the urinary tract may adversely affect prognosis and necessitate treatment of concurrent urinary tract disease.
Although 6 of 8 horses in the present report were hospitalized for 1 week or less, 2 horses had prolonged periods of hospitalization. Of the 2 horses hospitalized for > 1 week, 1 was hospitalized for 17 days and underwent several additional endoscopic procedures by use of laser lithotripsy to disrupt a nephrolith following removal of the cystic calculus. The second horse was hospitalized for 23 days to provide an extended period of postoperative medical management for treatment of severe ulcerative cystitis, which had been diagnosed on initial cystoscopic examination.
Three calculi removed from 2 horses in the present report were submitted for crystallographic analysis to definitively determine their composition. Interestingly, all 3 calculi were composed solely of calcium carbonate (type 1 uroliths), although they varied in gross appearance and resistance to fragmentation. This was likely attributable to differences between uroliths that have the same crystalline composition but vary in their microstructure.18 Typically, type 1 calculi have high porosity throughout, making them particularly susceptible to fragmentation. In the present report and a previous report,18 some type 1 calculi were found to have a porous center, with thick laminar bands of calcium carbonate making up the outer surface. These bands consisted of tightly aligned fibrous calcium carbonate crystals, which appeared to be structurally more stable and resistant to fragmentation.
The calculi removed from the remaining 6 horses of the present report were presumed to also be type 1 calcium carbonate uroliths on the basis of their spiculated yellow-green appearance and susceptibility to lithotripsy, although this could not be stated with absolute certainty because their composition was not evaluated. Because type 2 uroliths are more resistant to fragmentation,3 it is unknown whether the technique described here would be an efficacious treatment for larger type 2 cystic calculi if fragmentation was deemed necessary. If attempts to fragment this type of stone were unsuccessful, then laparocystotomy would be the treatment of choice for removal.
Limitations of the present retrospective case series included the small number of horses and the lack of longer-term follow-up. Nonetheless, findings suggested that use of the laparoscopic specimen retrieval pouch was a safe, rapid method for removal of cystic calculi from standing sedated horses regardless of whether intact removal was possible or fragmentation was necessary. The dimensions and durability of the pouch rendered it an effective means of protecting the urinary bladder and urethra of all horses from iatrogenic trauma as well as containment of debris when fragmentation was necessary to facilitate calculus removal. Use of the laparoscopic specimen retrieval pouch has the potential to reduce the incidence of intraoperative complications, postoperative morbidity rates, and risk of calculus recurrence or subsequent urinary tract obstruction associated with incomplete calculus removal from horses.
Footnotes
Epidural catheterization kit with TheraCath catheter, Arrow International, Reading, Pa.
Stallion urinary catheter, Jorgensen Labs, Loveland, Colo.
Fujinon EVE 400 Series, Fujinon, Wayne, NJ.
Endo catch II specimen retrieval pouch, Covidien, New Haven, Conn.
Vet One OB lube, MWI Veterinary Supply, Boise, Idaho.
Duolith Vet, Storz Medical, Tägerwilen, Switzerland.
Sharp & Smith, Chicago, Ill.
References
1. Laverty S, Pascoe JR, Ling GV, et al. Urolithiasis in 68 horses. Vet Surg 1992; 21: 56–62.
2. Holt PE, Pearson H. Urolithiasis in the horse—a review of 13 cases. Equine Vet J 1984; 16: 31–34.
3. Schott HC II, Woodie JB. Bladder. In: Auer JA, Stick JA, eds. Equine surgery. 4th ed. St Louis: Saunders/Elsevier, 2012;927–939.
4. Rocken M, Furst A, Kummer M, et al. Endoscopic-assisted electrohydraulic shockwave lithotripsy in standing sedated horses. Vet Surg 2012; 41: 620–624.
5. Hawkins JF. Clinical commentary: surgical treatment of urolithiasis in male horses. Equine Vet Educ 2013; 25: 60–62.
6. Duesterdieck-Zellmer KF. Equine urolithiasis. Vet Clin North Am Equine Pract 2007; 23: 613–629 (vi.).
7. Diaz-Espineira M, Escolar E, Bellanato J, et al. Structure and composition of equine uroliths. J Equine Vet Sci 1995; 15: 27–34.
8. Ines MM, Fitch G. Use of a laparoscopic retrieval device for urolith removal through a perineal urethrotomy. Vet Surg 2012; 41: 629–633.
9. Judy CE, Galuppo LD. Endoscopic-assisted disruption of urinary calculi using a holmium:YAG laser in standing horses. Vet Surg 2002; 31: 245–250.
10. Firth EC. Urethral sphincterotomy for delivery of vesical calculus in the mare: a case report. Equine Vet J 1976; 8: 99–100.
11. Beard W. Parainguinal laparocystotomy for urolith removal in geldings. Vet Surg 2004; 33: 386–390.
12. Ragle CA. Laparoscopic removal of cystic calculi. In: Fischer AT, ed. Equine diagnostic and surgical laparoscopy. Philadelphia: Saunders, 2002;229–234.
13. Rocken M, Stehle C, Mosel G, et al. Laparoscopic-assisted cystotomy for urolith removal in geldings. Vet Surg 2006; 35: 394–397.
14. Lund CM, Ragle CA, Lutter JD. Laparoscopic removal of a bladder urolith in a standing horse. J Am Vet Med Assoc 2013; 243: 1323–1328.
15. Abuja GA, Garcia-Lopez JM, Doran R, et al. Pararectal cystotomy for urolith removal in nine horses. Vet Surg 2010; 39: 654–659.
16. May KA, Pleasant RS, Howard RD, et al. Failure of holmium:yttriumaluminum-garnet laser lithotripsy in two horses with calculi in the urinary bladder. J Am Vet Med Assoc 2001; 219: 957–961, 939.
17. Howard RD, Pleasant RS, May KA. Pulsed dye laser lithotripsy for treatment of urolithiasis in two geldings. J Am Vet Med Assoc 1998; 212: 1600–1603.
18. Grant DC, Westropp JL, Shiraki R, et al. Holmium:YAG laser lithotripsy for urolithiasis in horses. J Vet Intern Med 2009; 23: 1079–1085.
19. Koenig J, Hurtig M, Pearce S, et al. Ballistic shock wave lithotripsy in an 18-year-old Thoroughbred gelding. Can Vet J 1999; 40: 185–186.
20. Schott HC II, Woodie JB. Urethra. In: Auer JA, Stick JA, eds. Equine surgery. 4th ed. St Louis: Saunders/Elsevier, 2012;940–949.
21. Traub-Dargatz JL, Wrigley RH. Ultrasonographic evaluation of the urinary tract. In: Rantanen NW, McKinnon AO, eds. Equine diagnostic ultrasonography. Baltimore: Williams & Wilkins, 1998;613–618.
