New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

3 CE Credits

Alice Defarges, DVM, DACVIM University of Guelph

Allyson Berent, DVM, DACVIM The Animal Medical Center New York, New York

Marilyn Dunn, DMV, DACVIM Université de Montreal

Abstract: Urolithiasis is a common clinical problem in small animal veterinary patients. Management of upper urinary tract calculi can be particularly challenging in small animals, as traditional surgical removal can be associated with significant morbidity. In humans, minimally invasive treatment options have replaced traditional surgical removal in many cases. This article reviews the current literature on the various types of lithotripsy and some of the newer minimally invasive options available for management of nephrolithiasis in small animal veterinary patients. An article in the January 2013 issue addressed management of lower urinary tract uroliths; a future article will discuss current management strategies for ureteroliths.

For more information, please see the companion article: Nephrolithiasis “New Alternatives for Minimally Invasive Management of Uroliths: Many canine and feline nephroliths remain static in size and Lower Urinary Tract Uroliths” (January 2013). clinically silent for years. Some controversy still exists as to whether nonobstructive kidney stones worsen underlying kidney disease.5 rolithiasis is a common clinical problem in small animal Removal of these stones is typically recommended if the stones veterinary patients. In the past, nephroliths were treated are increasing in size or if the patient has a partial or complete Umedically, via dissolution, or removed surgically by neph- ureteropelvic junction obstruction resulting in hydronephrosis, renal rostomy, nephrectomy, or pyelotomy. Management of calculi can parenchymal loss, worsening renal function, chronic hematuria, be challenging in small animals because traditional surgical removal pain, or recurrent infections.6 can be associated with significant morbidity1,2 and the incidence In small animals, traditional intervention for treatment of of stone recurrence in dogs and cats is high.3 Recurrence rates nephrolithiasis involves a nephrotomy, pyelotomy, or salvage depend on the type of urolith, the location of the stone, the sex of ureteronephrectomy. Complications can be severe and life- the patient, and whether effective techniques have been under- threatening after a nephrotomy and can include hemorrhage, taken to treat underlying causes of urolith formation. Appropriate decreased renal function, ureteral obstruction by remaining medical therapy (e.g., dietary therapy, chelation therapy, diuresis, nephrolith fragments, and urinary leakage into the abdomen from antimicrobial therapy), follow-up imaging, urinalysis, and urine the renal incision.7,8 In a study of normal cats, the glomerular culture are indicated to minimize the potential for recurrence filtration rate (GFR) of the ipsilateral kidney decreased 10% to 20% of calculi. However, the recurrence rate remains high despite after a nephrotomy.8 This was clinically insignificant in normal cats, preventive therapy, which has led to the investigation of newer but in a clinical patient with maximally hypertrophied nephrons minimally invasive treatment options for veterinary patients to due to prior nephrolith-induced damage, the significance could be avoid the need for serial invasive procedures. In humans, minimally dramatic. Therefore, feline patients with an already compromised invasive treatment options have, in most cases, replaced traditional GFR from chronic stone disease may develop a clinically significant surgical removal.4 decline in renal function after nephrotomy.8 Also, the >30% of Dr. Berent has been an advisor for Infiniti Medical, LLC. adult cats that develop chronic kidney disease resulting in a 67% Dr. Dunn discloses that she has received financial benefits from Infiniti Medical and Vétoquinol. to 75% decline of renal function8 cannot tolerate a 10% to 20%

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E1

New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

Box 1. Candidates for Extracorporeal Shock-Wave Lithotripsy

Nephroliths (in dogs) Indications • Hydronephrosis • Recurrent infection • Pain • Worsening chronic renal failure

Stone size • <10 mm: ESWL alone • >10–25 mm: ESWL with ureteral stent or PCNL • >25 mm: consider PCNL Ureteroliths Indications Figure 1. Dry lithotripter (Modulith, Storz). Courtesy of John Denstedt, MD, • Causing ureteral obstruction FRCSC, FACS, Western University, London, Ontario • Pain (BOX 1). There are two types of ESWL unit: “wet” and “dry.” Wet units • Recurrent infection are no longer available and are only used in research settings. The Patient characteristics newer dry units allow better imaging, better focus, and less scat- • Dogs with nephroliths or ureteroliths; cats with distal ureteroliths tering of shock waves. Because the shock waves produced are more closely focused on the stone, dry units provoke less peripheral • Normal coagulation status parenchymal damage17 but have the potential to induce more • Not pregnant trauma to the kidney itself. Methods to minimize renal injury in humans are under investigation and may include changes in shock- • No evidence of concurrent pancreatitis wave rate, modification of power settings, and administration of 18–20 • Appropriate antibiotic therapy for >48 hours before ESWL renoprotective agents like allopurinol. Renal injury does not seem to be a major concern in the few dogs treated to date, but it ESWL = extracorporeal shock-wave lithotripsy, PCNL = percutaneous nephrolithotomy. is currently under investigation in cats. For ESWL, the patient is placed under general anesthesia to further decline in GFR. Hence, nephrotomy should be avoided when permit positioning and provide analgesia. Fluoroscopy is used to possible in all cats, especially those with existing renal disease.8,9 position the ESWL unit to target the urolith(s) (FIGURE 1). Neph- In humans, minimally invasive procedures are typically the roliths are typically fragmented with a total of 1000 to 3000 shock treatments of choice for nephrolithiasis. These procedures include waves per kidney at 16 to 18 kV with a wet lithotripter (e.g., Dornier extracorporeal shock-wave lithotripsy (ESWL) for nephroliths HM-3, Wessling, Germany)14 or a total of 900 to 3500 shock <1 to 2 cm and percutaneous nephrolithotomy (PCNL) for neph- waves per kidney with a dry lithotripter (e.g., Modulith SL-20, roliths >1 to 2 cm. Open surgery and laparoscopy are rarely nec- Karl Storz Lithotripsy, Kennesaw, GA)15. If compromised renal essary and are usually considered only after other, less invasive, function is of concern, or if bilateral ESWL is to be performed options have failed or have been deemed inappropriate.4,10 Many concurrently, I (A. B.) recommend treating to a maximum of 2000 human studies have shown ESWL and PCNL to have a minimal to 2500 shock waves per kidney. effect on the GFR of clinical stone-forming patients, particularly when compared with traditional surgical nephrotomy.11–13 These Patient Selection and Potential Complications procedures, particularly PCNL, have been shown to be highly ESWL is most commonly recommended for treatment of neph- effective in removing all stone fragments, as endoscopic calyceal roliths in dogs, rather than cats, for two reasons. First, the feline inspection is superior for visualization and fragment retrieval ureter does not routinely accommodate nephrolith fragment compared with nephrotomy.11–13 passage. Post-ESWL nephrolith fragments are typically ≥1 mm in diameter, and the typical unstented feline ureter is 0.3 to 0.4 mm Extracorporeal Shock-Wave Lithotripsy in diameter. It is very important that a nonobstructive nephrolith not ESWL is a minimally invasive method used to fragment uroliths become an obstructive ureterolith, particularly in a feline patient. fixed in one location. It has been successfully used to fragment Second, there is some concern that feline kidneys are more sensi- nephroliths and ureteroliths in dogs and ureteroliths in cats14–16 tive than canine kidneys to shock waves and could experience

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E2

New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

dogs required more than one ESWL treatment for adequate frag- Box 2. Urolith Composition in Order of Ease of Fragmentation 14 (Least to Most Resistant)15,22–24 mentation of nephroliths when wet lithotripsy was used ; when an old dry unit (Modulith SL-20) was used, up to 50% of dogs required • Struvitea • Urate more than one treatment.15 In my (A. B.) experience, the newer dry units are more powerful and effective, with a more focused • Calcium oxalate dihydrate • Cystine beam, resulting in lower stone retreatment rates. Approximately • Calcium oxalate monohydrate 15% of cases need a second treatment, although our practice is to empirically place a concurrent ureteral stent in dogs with stones aIn humans, struvite stones are considered harder to fragment than calcium oxalate, although this has not been my (A. B.) experience when using intracorporeal lithotripsy or extracorporeal shock-wave lithotripsy >1 cm. Success is stone and patient dependent. Stone size and in companion animals. composition are clearly associated with success in human urology, and the same seems to be true in veterinary medicine. life-threatening bleeding.14–16 Bleeding can occur in both species, In a series of 140 dogs with nephroliths or ureteroliths treated by but the limited experience in cats resulted in one case having more ESWL,30 the most common complication was ureteral obstruction severe hematuria than that seen in more than 150 dogs. This by stone fragments, which occurred in approximately 10% of finding requires more investigation to confirm. Gonzales et 21al dogs. With the advocacy of ureteral stent placement for larger found no significant effects on the ultrasonographic appearance nephroliths (>1 cm) before ESWL, this risk has declined. The of stone-free feline kidneys at 24 hours and 14 days after ESWL presence of the ureteral stent may facilitate the passage of the using a Dornier MFL-5000 lithotripter. Additionally, there was stones due to passive ureteral dilation and helps to improve fluo- no difference in GFR measured before and 14 days after treatment roscopic identification of small ureteral stones during the ESWL in these cats.21 While these results are promising, the shock-wave treatment, making treatment more effective.31,32 dosage used in healthy cats in this study may not be adequate to sufficiently fragment feline uroliths, and diseased feline kidneys Use of Stents likely respond differently to the effects of ESWL than healthy Ureteral stents have been placed in dogs to improve stone fragment kidneys15 because of the hypertrophy mechanisms, which may passage after lithotripsy. In my (A. B.) experience, success rates have previously been exhausted. Feline upper-tract uroliths are approach ~85% with one treatment when ureteral stenting is typically composed of calcium oxalate monohydrate rather than concurrently performed. Stents are typically placed to prevent calcium oxalate dihydrate, and these stones are also considered to subsequent ureteral obstruction and allow for passive ureteral be harder and more difficult to fragment with ESWL (BOX 2).15,22–24 dilation (in my experience [AB]). Stent-induced passive ureteral ESWL is believed to be safe and well tolerated by canine kidneys.16 dilation is beneficial in cases The severity of the renal damage is dose dependent. In dogs, it has with large nephroliths (1 been shown that the renal changes observed after ESWL typically cm), as the risk of develop- result in minimal decreases in GFR and renal blood flow during ing a ureteral obstruction the first 24 hours of treatment, and both return to baseline within 1 during passage is the major week.14,25,26 Intrarenal hemorrhage does occur in dogs and is typically concern (FIGURE 2). Animals short-lived.14,16 In one study, minor, transient changes in post- with ureteral stents often retreatment creatinine levels occurred in four dogs with preexisting quire shorter hospital stays, azotemia.27 Pre- and postprocedural diuresis is recommended in as the concern for post- all patients. ESWL ureteral obstruction Extrarenal complications with ESWL include abdominal pain, is diminished. There is some diarrhea, and pancreatic injury (i.e., increased amylase, lipase, evidence in research models liver enzyme, and trypsin-like immunoreactivity levels). Shock that ureteral stenting may wave–induced “pancreatitis” occurred in approximately 2% to diminish ureteral peristal- 3% of dogs treated by ESWL in one study, based on elevated bio- sis,33,34 which may ultimately chemical parameters.28 In the author’s (A. B.) experience, this result in slower stone pas- complication is rarely associated with clinical signs. Shock wave– sage after ESWL.35,36 For this induced dysrhythmias (e.g., ventricular extrasystole, atrial extra- reason, patients with stented systole, sinus bradycardia) have occurred in a few human patients ureters are typically given (<8%); this rate has declined since the development of the dry 3 months to pass stone Figure 2. Patient before and after ESWL and lithotripter and the ability to deliver shock waves in a gated fashion fragments before a second ureteral stenting. (A) Abdominal radiograph with the cardiac rhythm.29 treatment is considered. showing bilateral nephroliths in the left renal ESWL treatment was reported to be successful in approximately pelvis of a dog, immediately before and 85% of dogs with calcium-containing nephroliths and ureteroliths.14 Follow-Up after ESWL and ureteral stent placement. (B) Enlarged image of a nephrolith in the left Successful fragmentation of renal stones was achieved in 90% of Postprocedure analgesia is renal pelvis before and after ESWL. dogs, but some dogs required two treatments.14 Overall, 30% of typically accomplished with

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E3

New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

tramadol (dogs: 3–5 mg/kg PO q6–8h) and buprenorphine (cats: 0.005–0.02 mg/kg IV, IM q4–8h). Hospitalization typically ranges from 8 to 24 hours to monitor for the passage of urolith fragments14–16 and to allow postprocedure diuresis with intravenous fluid therapy. Patients may need to be monitored for a few extra days to ensure no ureteral obstruction develops, particularly those without a ureteral stent. Stone fragments may be voided 1 or 2 days after the procedure and collected in a strainer or cheesecloth to be analyzed. Patients are discharged with instructions for monitoring urination and urine appearance, lethargy, abdominal pain, or vomiting. Small amounts of blood may be seen in the urine for the first 18 to 24 hours. A standard medical approach is started based on urolith composition. Follow-up radiography and ultrasonography are typically recommended 1 day after treatment, then in 2 to 4 weeks, and then every month thereafter until all stones are passed.14–16 A Figure 3. PCNL in a 6.8-lb (3.1-kg) Yorkshire terrier. (A) Percutaneous renal pelvis access obtained using fluoroscopic guidance. The sheath ( ) is placed second treatment is required in 15% to 35% of cases to achieve black arrow through the body wall, through the kidney, and onto the stone (white asterisk) in effective fragmentation if the remaining fragments appear too the renal pelvis. This was all done over a guide wire (white arrows) inside the large to safely pass through the ureter.14,16 If fragments that have ureteral lumen. (B) A nephroscope (white arrow) is advanced through the access passed into the urinary bladder are not voided within 1 or 2 sheath to perform lithotripsy and break up the stone (black arrowheads). (C) months after ESWL, voiding urohydropulsiona or cystoscopic Fluoroscopy image showing removal of the stone fragments. (D) The nephroscope is placed through the sheath. (E) Endoscopic image of the calcium oxalate stone stone basketing is recommended.14 If stone fragments remain in inside the renal pelvis with the lithotripsy probe on the stone (black asterisk). the kidney or ureter after 2 or 3 months, repeat ESWL is sug- gested as long as there is no concurrent ureteral obstruction. In cases of ureteral obstruction, placement of a ureteral stent is combination is advanced over a guide wire through the renal pa- recommended.b renchyma, into the renal pelvis, and onto the nephrolith. A mini- We do not recommend repeat ESWL of nephroliths within 4 PCNL approach using an 18- or 24-French access kit is used for weeks; however, there are no veterinary references supporting smaller patients. Once the sheath is in the renal pelvis, a nephroscope our clinical practices. The optimal time to carry out a repeat is used to identify the stone. If the stone is small enough, a stone- treatment of the same kidney has not been adequately studied, retrieval basket is used to remove it. If the stone is larger than the even in humans. A wait time of 2 weeks has been discussed in sheath, intracorporeal lithotripsy (ultrasonic, electrohydraulic, human medicine to allow enough time for stone passage before or Ho:YAG [holmium:yttrium, aluminum, garnet] laser) is used re-treating. By extrapolation, as stones are expected to pass within to fragment it (FIGURE 3 and VIDEO 1*). Once the stone fragments 4 weeks after ESWL in dogs, we recommend waiting 4 weeks before are small enough to fit through the sheath, they are removed. If more re-treating the same kidney. than one stone is present, the sheath and scope can remain in the renal pelvis until all stones have been fragmented and removed. Percutaneous Nephrolithotomy A locking-loop nephrostomy tube (5 or 6 Fr) is left in place to In humans, PCNL is typically performed for large or impacted allow the small hole to seal and form a nephropexy.39 nephroliths (>15 to 30 mm).37,38 In small animals, PCNL is con- Surgical-assisted endoscopic nephrolithotomy (SENL) is a sidered if ESWL fails or is not available, if cystine stones (which PCNL-like procedure that is performed using a rigid endoscope are resistant to EWSL) are present, or if the stone is >15 mm. PCNL during an open laparotomy, resulting in excellent magnification has been performed in a handful of canine patients to date, as of the renal pelvis for stone retrieval.40,41 For this procedure, the well as a feline patient. Typically, a combination of ultrasono- greater curvature of the kidney is punctured with a renal access graphic, endoscopic, and fluoroscopic guidance is used. Patient needle and pyelography is performed. A guide wire is then advanced size is less of a factor for PCNL than for ureteroscopy; the smallest into the renal pelvis under fluoroscopic guidance, and a balloon canine patient in which I (A. B.) have successfully performed dilation catheter, preloaded with a matching sheath, is advanced PCNL weighed only 6.8 lb (3.1 kg). over the wire onto the nephrolith. The balloon is dilated, and the Typically, for PCNL, a renal access needle is used to access the sheath slides smoothly over the balloon. The balloon is then renal pelvis through the greater curvature of the kidney under withdrawn, and the scope is inserted through the sheath for ultrasonographic guidance. Subsequently, using fluoroscopic stone removal. The stone can be removed with a basket if it is guidance, a sheath (12 to 30 Fr) and balloon dilation catheter small enough to pass through the sheath, or it can be fragmented by lithotripsy before being removed. Using a balloon-sheath aFor more information on voiding urohydropulsion, see “New Alternatives for Minimally Invasive Management of Uroliths: Lower Urinary Tract Uroliths” in the January 2013 issue of Compendium. combination creates a tamponade effect so that there is very little bUreteral stent placement will be discussed in more detail in the third article in this series, “New risk of hemorrhage. For SENL, a nephrostomy tube is not necessary Alternatives for Minimally Invasive Management of Uroliths: Ureteroliths.” *To watch the video referred to in this article, please visit www.vetlearn.com.

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E4

New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

Box 3. Hospitals Routinely Performing Minimally Invasive above have been performed in a small number of patients in only Procedures to Treat Nephroliths a few facilities; therefore, they are still considered investigational. Minimally invasive management of urolithiasis in veterinary The Animal Medical Center medicine is following the trend seen in human medicine. Over 510 E. 62nd Street the past 10 years, the veterinary community has made great New York, NY 10065 strides in adapting the technology used for humans to be more Contact: Dr. Allyson Berent applicable to small animal veterinary patients. Conditions that Email: [email protected] have traditionally been considered a major therapeutic dilemma, Phone: 212-838-8100 like ureteral obstructions, kidney stone recurrence, and urethral Currently performing extracorporeal shock-wave lithotripsy, percutaneous obstructions, now have new, effective, and safe options. nephrolithotomy, and surgical-assisted endoscopic nephrolithotomy References Purdue University School of Veterinary Medicine 1. Gookin JL, Stone EA, Spaulding KA, Berry CR. Unilateral nephrectomy in dogs with West Lafayette, IN 47906 renal disease: 30 cases (1985-1994). J Am Vet Med Assoc 1996;208:2020-2026. 2. Kyles AE, Hardie EM, Wooden BG, et al. Management and outcome of cats with ureteral Contact: Dr. Larry Adams calculi: 153 cases (1984-2002). J Am Vet Med Assoc 2005;226:937-944. Email (Referral desk): [email protected] 3. Brown NO, Parks JL, Greene RW. Recurrence of canine urolithiasis. J Am Vet Med Assoc Currently performing extracorporeal shock-wave lithotripsy 1977;170:419-420. 4. Anoia EJ, Resnick MI. Open stone surgery. In: Stoller ML, Meng MV, eds. Urinary Stone Disease: A Practical Guide to Medical and Surgical Management. Totowa, NJ: Humana Press Inc.; 2007:639-650. because the hole can be closed by direct suturing of the renal 5. Ross SJ, Osborne CA, Lekcharoensuk C, et al. A case-control study of the effects of capsule. Because a balloon is used to dilate the renal parenchyma, nephrolithiasis in cats with chronic kidney disease. J Am Vet Med Assoc 2007;230:1854-1859. minimal nephron loss occurs and the tissue does not need to be 6. Stone EA, Gookin J. Indications for nephrectomy and nephrotomy. In: Bonagura J, ed. incised. SENL is now being performed routinely on canine kidneys Current Veterinary Therapy XIII: Small Animal Practice. Philadelphia: WB Saunders; in my practice (A. B.). 2000:866-867. 7. Gahring DR, Crowe DT Jr, Powers TE, et al. Comparative renal function studies of ne- Other surgical-assisted approaches place the scope through a phrotomy closure with and without sutures in dogs. J Am Vet Med Assoc 1977;171:537-541. blunt puncture in the greater curvature (lateral margin) of the 8. Bolliger C, Walshaw R, Kruger JM, et al. Evaluation of the effects of nephrotomy on kidney until it penetrates the pelvis. Calculi can be removed by renal function in clinically normal cats. Am J Vet Res 2005;66:1400-1407. using a stone retrieval basket placed through the operating channel 9. King MD, Waldron DR, Barber DL, et al. Effect of nephrotomy on renal function and of the cystoscope. morphology in normal cats. Vet Surg 2006;35:749-758. Unlike nephrotomy, PCNL and SENL do not require transient 10. Ramani AP, Gill IS. Laparoscopic approach to urinary stone disease. In: Stoller ML, Meng MV, eds. Urinary Stone Disease: A Practical Guide to Medical and Surgical Man- occlusion of renal vessels, and they result in a much smaller hole agement. Totowa, NJ: Humana Press Inc.; 2007:651-659. in the renal parenchyma than a nephrotomy. Placing sutures in 11. Gupta R, Kumar A, Kapoor R, et al. Prospective evaluation of the safety and efficacy of the capsule and apposing the small incision can close the renal the supracostal approach for percutaneous nephrolithotomy. BJU Int 2002;90:809-813. access point. The use of the endoscope also allows differentiation 12. Elbahnasy AM, Clayman RV, Shalhav AL, et al. Lower-pole caliceal stone clearance between intraluminal calculi and mural calcification, which can also after shockwave lithotripsy, percutaneous nephrolithotomy, and flexible ureteroscopy: impact of radiographic spatial anatomy. J Endourol 1998;12:113-119. be assessed before surgery with the use of computed tomography– 13. Meretyk S, Gofrit ON, Gafni O, et al. Complete staghorn calculi: random prospective intravenous pyelography. Care must be taken to assess all areas of comparison between extracorporeal shock wave lithotripsy monotherapy and combined the renal pelvis and renal calices, as small calculi can remain if with percutaneous nephrostolithotomy. J Urol 1997;157:780-786. fluoroscopy and contrast nephrography are not used concurrently. 14. Adams LG, Senior DF. Electrohydraulic and extracorporeal shock-wave lithotripsy. We recommend the use of fluoroscopy when performing PCNL Vet Clin North Am Small Anim Pract 1999;29:293-303. 15. Lane IF. Lithotripsy: an update on urologic applications in small animals. Vet Clin and SENL to identify any remaining stone fragments in the renal North Am Small Anim Pract 2004;34:1011-1025. 10 calices. This is also recommended in human urology. 16. Lulich JP, Adams LG, Grant D, et al. Changing paradigms in the treatment of uroliths by lithotripsy. Vet Clin North Am Small Anim Pract 2009;39:143-160. Conclusion 17. Chow GK, Streem SB. Extracorporeal lithotripsy: update on technology. Urol Clin ESWL is an efficient minimally invasive technique for the treatment North Am 2000;27:315-322. 18. Auge BK, Preminger GM. Update on shock wave lithotripsy technology. Curr Opin of upper urinary tract calculi (nephroureterolithiasis) in dogs, Urol 2002;12:287-290. provided that the candidates are well selected and the facility is 19. Munver R, Delvecchio FC, Kuo RL, et al. In vivo assessment of free radical activity prepared for the management of animals with upper urinary during shock wave lithotripsy using a microdialysis system: the renoprotective action of tract obstructions if a ureteral obstruction occurs (BOX 3). The use allopurinol. J Urol 2002;167:327-334. of concurrent ureteral stenting in veterinary medicine has made 20. Paterson RF, Kuo RL, Lingeman JE. The effect of rate of shock wave delivery on the efficiency of lithotripsy. 2002;12:291-295. ESWL safer for small dogs with large stone burdens. PCNL is the Curr Opin Urol 21. Gonzalez A, Labato M, Solano M, Ross L. Evaluation of the safety of extracorporeal best minimally invasive alternative to remove large stone burdens shock-wave lithotripsy in cats [abstract]. J Vet Intern Med 2002:810. in the kidney (>1.5 to 2 cm), particularly when ESWL fails. It is 22. Adams LG, Williams JC Jr, McAteer JA, et al. In vitro evaluation of canine and feline important to remember that many of the procedures described calcium oxalate urolith fragility via shock wave lithotripsy. Am J Vet Res 2005;66:1651-1654.

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E5

New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

23. Wang DW, Wang JY, Cao XM. Compare the outcome of ureteroscopic lithotripsy with 33. Jones BJ, Ryan PC, Lyons O, et al. Use of double pigtail stent in stone retrieval following ureteroscopic management after failed extracorporeal shock wave lithotripsy for ureteral unsuccessful ureteroscopy. Br J Urol 1990;66:254-256. calculi. Zhonghua Wai Ke Za Zhi 2009;47:258-260. 34. Patel U, Kellett MJ. Ureteric drainage and peristalsis after stenting studied using 24. Williams JC Jr, Saw KC, Paterson RF, et al. Variability of renal stone fragility in shock colour doppler ultrasound. Br J Urol 1996;77:530-535. wave lithotripsy. Urology 2003;61:1092-1096; discussion 1097. 35. Mustafa M, Ali-El-Dein B. Stenting in extracorporeal shockwave lithotripsy; may 25. Lingeman JE, Lifshitz DA, Evan AP. Surgical management of urinary lithiasis. In: Walsh enhance the passage of the fragments! J Pak Med Assoc 2009;59:141-143. PC, ed. Campbell’s Urology. 8th ed. Philadelphia, PA: WB Saunders; 2002:3361-3451. 36. Chandhoke PS, Barqawi AZ, Wernecke C, Chee-Awai RA. A randomized outcomes 26. Hill DE, McDougal WS, Stephens H, et al. Physiologic and pathologic alterations trial of ureteral stents for extracorporeal shock wave lithotripsy of solitary kidney or proximal associated with ultrasonically generated shock waves. J Urol 1990;144:1531-1534. ureteral stones. J Urol 2002;167:1981-1983. 27. Block G, Adams LG, Widmer WR, Lingeman JE. Use of extracorporeal shock wave 37. Al-Awadi K, Kehinde EO, Al-Hunayan A, Al-Khayat A. Iatrogenic ureteric injuries: lithotripsy for treatment of nephrolithiasis and ureterolithiasis in five dogs.J Am Vet Med incidence, aetiological factors and the effect of early management on subsequent outcome. Assoc 1996;208:531-536. Int Urol Nephrol 2005;37:235-241. 28. Daugherty MA, Adams LG, Baird DK, et al. Acute pancreatitis in two dogs associated 38. Sofikerim M. Percutaneous nephrolithotomy: indications and technique. Erciyes with shock waves lithotripsy [abstract]. J Vet Intern Med 2004;18:441. Med J 2008;30:30-36. 29. Zanetti G, Ostini F, Montanari E, et al. Cardiac dysrhythmias induced by extracorporeal 39. Parks JL, Meng MV, Stoller ML. Percutaneous nephrolithotomy—technical aspects. shockwave lithotripsy. J Endourol 1999;13:409-412. In: Stoller ML, Meng MV, eds. Urinary Stone Disease: The Practical Guide to Medical 30. Lulich JP, Osborne CA, Albasan H, et al. Efficacy and safety of laser lithotripsy in and Surgical Management. Totowa, NJ: Humana Press; 2007:621-638. fragmentation of urocystoliths and urethroliths for removal in dogs. J Am Vet Med Assoc 40. McCarthy TC. Otheroscopies. In: McCarthy TC, ed. Veterinary Endoscopy for the 2009;234:1279-1285. Small Animal Practitioner. St. Louis, MO: Elsevier Saunders; 2005:423-445. 31. Finney RP. Experience with new double j ureteral catheter stent. J Urol 1978;120:678-681. 41. Rawlings C. Surgical views: endoscopic removal of urinary calculi. Compend Contin 32. Brewer AV, Elbahnasy AM, Bercowsky E, et al. Mechanism of ureteral stent flow: a Educ Vet 2009;31:476-484 comparative in vivo study. J Endourol 1999;13:269-271.

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E6

New Alternatives for Minimally Invasive Management of Uroliths: Nephroliths

This article qualifies for 3 contact hours of continuing education credit from the Auburn University College of Veterinary Medicine. CE tests must be taken online at Vetlearn.com; test results and CE certificates are available immediately. Those who wish to apply this credit to 3 CE Credits fulfill state relicensure requirements should consult their respective state authorities regarding the applicability of this program.

1. Removal is indicated for upper urinary tract stones that are b. cardiac arrhythmias a. obstructing urine flow. c. ureteral obstruction b. causing hydroureter/hydronephrosis. d. pancreatitis c. associated with discomfort or recurrent pyelonephritis. 7. All of the following are indications for treatment with ESWL d. all of the above in dogs except 2. After nephrotomy, the glomerular filtration rate in a cat a. pregnancy a. increases by 10% to 20%. b. hydronephrosis b. increases by 30% to 50%. c. stone size <10 mm c. decreases by 10% to 20%. d. pain d. decreases by 20% to 30%. 8. Which statement is false with regard to percutaneous 3. Which treatment option should be considered first for a dog nephrolithotomy (PCNL)? with a 25-mm nephrolith obstructing the renal pelvis? a. PCNL requires a ureterotomy to access the renal pelvis. a. nephrotomy b. Once the sheath is in the renal pelvis, a nephroscope is b. percutaneous nephrolithotomy used to identify the stone. c. extracorporeal shock-wave lithotripsy c. Access to the renal pelvis is gained percutaneously through d. ureteronephrectomy the greater curvature using fluorosocopic guidance and a renal access needle. 4. Extracorporeal shock-wave lithotripsy (ESWL) treatment d. PCNL is typically performed for large, impacted nephroliths was reported to be successful in approximately _____ of in people. dogs with calcium-containing nephroliths and ureteroliths. a. 50% 9. Which statement regarding surgical-assisted endoscopic b. 65% nephrolithotomy is false? c. 70% a. It is performed using a rigid endoscope during an open d. 85% laparotomy. b. It results in excellent magnification of the renal pelvis for 5. With a traditional wet lithotripter, reintervention was reported stone removal. to be necessary in ______of patients with nephroliths. c. A nephrostomy tube is necessary in all patients. a. 5% d. Calculi can be removed with a stone retrieval basket. b. 10% c. 30% 10. Which statement is false with regard to ESWL? d. 50% a. Cats with nephroliths are not good candidates for ESWL.

6. What is the most common complication after ESWL to treat b. Diuresis is required after this procedure. upper urinary tract stones? c. ESWL requires the patient to be under general anesthesia. a. acute renal failure d. ESWL uses a laser to fragment uroliths.

Vetlearn.com | February 2013 | Compendium: Continuing Education for Veterinarians® E7