Ureteroneocystostomy for treatment of struvite urolithiasis in a ferret.

OBJECTIVE: To assess the clinical outcome of a ferret undergoing a ureteroneocystostomy for treatment of urolithiasis. ANIMAL: A 10-month-old spayed female ferret. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The ferret was evaluated for straining to urinate and defecate, hematochezia, and a rectal prolapse. Plain radiographs revealed large cystic and ureteral calculi. Clinicopathologic analyses indicated the ferret was anemic with an elevated creatinine concentration. Exploratory laparotomy defined bilateral ureteral calculi that were unable to be successfully moved into the bladder. A cystotomy was performed to remove a large cystic calculus. Serial abdominal ultrasonographic examinations showed progressive hydronephrosis of the left kidney and persistent pyelectasia of the right kidney secondary to bilateral ureteral calculi. This confirmed a left ureteral obstruction secondary to the distal calculus while the right ureter remained patent. TREATMENT AND OUTCOME: A ureteroneocystostomy was performed to allow for left renal decompression. The ferret recovered well despite worsening hydronephrosis of the left kidney in the perioperative period. The ferret was discharged from the hospital 10 days after initial evaluation. At 3-week follow-up, abdominal ultrasonography confirmed resolution of hydronephrosis and ureteral dilation of the left kidney and ureter. CLINICAL RELEVANCE: A ureteroneocystostomy successfully allowed renal decompression and ureteral patency in a ferret with urolithiasis. To the authors' knowledge, this is the first time this procedure has been reported in a ferret for treatment of a ureteral calculus obstruction and may result in good long-term outcome.

Minimally invasive removal of obstructive ureteral stones by intracorporeal lithotripsy in horses: 3 patients.

Three client-owned horses diagnosed with obstructive ureteral stones were referred and treated in a minimally invasive manner by retrograde ureteroscopy in conjunction with electrohydraulic lithotripsy (EHL) or laser Holmium:YAG lithotripsy (HYL). For all 3 horses, additional tests revealed variable degrees of azotemia and ureteral obstruction. Ultrasound examination (2 horses) revealed a loss of cortico-medullary distinction consistent with a chronic nephropathy. Ultrasound-guided biopsy of the right kidney in 1 horse revealed moderate glomerulosclerosis and lymphoplasmacytic nephritis. A standing anesthesia with a coccygeal epidural was done for each horse. A perineal urethrotomy was performed in 2 horses before the urethrocystoscopy. One horse was treated with Holmium:YAG laser lithotripsy and 2 others were treated using a electrohydraulic lithotripsy probe. Each procedure was successful. The ureteroscopy was successfully performed and visualization was excellent. Fragmentation of stones seemed easier with the electrohydraulic lithotripsy probe. No complications, pain, or signs of discomfort after the procedure were noticed. All 3 horses were discharged from the hospital. Key clinical message: Obstructive ureteral stones in horses can be successfully treated in a minimally invasive manner by retrograde ureteroscopy accompanied by lithotripsy. This technique is safe, not painful and did not require general anesthesia. Electrohydraulic lithotripsy appeared superior for stone fragmentation.

Exérèse minimalement invasive de calculs urétéraux obstructifs par lithotritie intracorporelle chez le cheval : trois patients. Trois chevaux appartenant à des clients diagnostiqués avec des calculs urétéraux obstructifs ont été référés et traités de manière peu invasive par urétéroscopie rétrograde en conjonction avec une lithotripsie électrohydraulique (EHL) ou une lithotripsie au laser Holmium:YAG (HYL). Pour les trois chevaux, des tests supplémentaires ont révélé des degrés variables d'azotémie et d'obstruction urétérale. L'échographie (deux chevaux) a révélé une perte de distinction cortico-médullaire compatible avec une néphropathie chronique. La biopsie échoguidée du rein droit chez un cheval a révélé une glomérulosclérose modérée et une néphrite lymphoplasmocytaire. Une anesthésie debout avec une péridurale coccygienne était effectuée pour chaque cheval. Une urétrotomie périnéale a été réalisée chez deux chevaux avant l'urétrocystoscopie. Un cheval a été traité par lithotripsie au laser Holmium:YAG et deux autres ont été traités à l'aide d'une sonde de lithotripsie électrohydraulique. Chaque procédure a réussi. L'urétéroscopie a été réalisée avec succès et la visualisation était excellente. La fragmentation des calculs semblait plus facile avec la sonde de lithotripsie électrohydraulique. Aucune complication, douleur ou signe d'inconfort après la procédure n'a été remarqué. Les trois chevaux ont obtenu leur congé de l'hôpital.Message clinique clé :Les calculs urétéraux obstructifs chez les chevaux peuvent être traités avec succès de manière peu invasive par urétéroscopie rétrograde accompagnée de lithotripsie. Cette technique est sûre, non douloureuse et ne nécessite pas d'anesthésie générale. La lithotritie électrohydraulique est apparue supérieure pour la fragmentation des calculs.(Traduit par Dr Serge Messier).

Endoscopic-guided laser lithotripsy for removal of an encrusted ureteral stent in a dog.

CASE DESCRIPTION: An 8-year-old spayed female Dalmatian was evaluated because of recurrent urinary tract infections following ureteral stent placement 3 years earlier. CLINICAL FINDINGS: Polyuria, pollakiuria, and hematuria were reported by the owner. Abdominal radiography revealed well-defined, faintly mineralized material superimposed over the distal portion of the previously placed ureteral stent. Abdominal ultrasonography revealed thickening of the bladder wall, right hydroureter, and right pyelectasia; the ureteral stent appeared to extend into a region containing cystic calculi. Cystoscopy revealed small uroliths and mineralized encrustation of the distal portion of the ureteral stent. TREATMENT AND OUTCOME: A holmium:yttrium-aluminum-garnet laser was used to fragment mineralized material from the distal end of the stent and allow endoscopic transurethral removal. Stone analysis revealed ammonium urate as the major component of the mineralized material. The owner was instructed to feed the dog a diet formulated to decrease the likelihood of urate stone recurrence and to administer marbofloxacin for 6 weeks because of suspected pyelonephritis. Follow-up bacterial culture of a urine sample and abdominal ultrasonography revealed resolution of urinary tract infection, pyelectasia, hydroureter, and associated clinical signs. CLINICAL RELEVANCE: Results suggested that endoscopic-guided laser lithotripsy can be used as a minimally invasive alternative to surgery for removal of severely encrusted ureteral stents in dogs.

Radiographic distribution of ureteral stones in 78 cats.

OBJECTIVE: To document the distribution of ureteral stones in cats. STUDY DESIGN: Retrospective case series. ANIMALS: Seventy-eight cats. METHODS: Abdominal radiographs with ureteral stones were reviewed. The location of stones was categorized as proximal ureter (PU), midureter (MU), or ureterovesicular junction (UVJ). The number, size, and location of stones were recorded by using the kidneys and vertebral bodies as landmarks. Stone location in cats with 1 versus multiple stones was assessed. Descriptive statistics were used to describe the incidence of ureteral stone location. RESULTS: Among cats with a single stone (44%, 34/78), 44% (15/34) had a stone in the PU, 41% (14/34) had a stone in the MU, and 15% (5/34) had a stone at the UVJ. When multiple stones were present, 61% (27/44) of cats had at least 1 stone located in the PU, 70% (31/44) had at least 1 stone located in the MU, and 34% (15/44) had at least 1 stone located at the UVJ. The L4 vertebral body most commonly marked stone location in cats with 1 stone and the most distal stone in cats with multiple stones. Stones located at the UVJ site were more common in male (37%) than in female (12%) cats (P = 0.004). Larger stone size was associated with a more proximal location (P = 0.04). CONCLUSION: Ureteral stones were more commonly located in the PU and the MU than in the UVJ. UVJ stones were more common in male than in female cats, and larger stones had a more proximal location. CLINICAL SIGNIFICANCE: This study enhances our understanding of feline ureteral stone location and identifies a correlation between stone location and stone size.

Calcium carbonate obstructive urolithiasis in a red kangaroo (Macropus rufus).

A 6-yr-old male red kangaroo (Macropus rufus) presented for a history of inappetance, abnormal behavior, and unconfirmed elimination for 6 hr prior to presentation. Based on abdominal ultrasound, abdominocentesis, and cystocentesis, a presumptive diagnosis of urinary tract obstruction with uroabdomen and hydronephrosis was reached. Abdominal radiographs did not assist in reaching an antemortem diagnosis. Postmortem examination confirmed a urinary bladder rupture secondary to urethral obstruction by a single urethrolith. Bilateral hydronephrosis and hydroureter were identified and determined to be a result of bilateral ureteroliths. Urolith analysis revealed a composition of 100% calcium carbonate. A dietary analysis was performed, implicating an increased Ca:P ratio from a food preparation miscommunication as a contributing factor. Appropriate husbandry changes were made, and mob surveillance procedures were performed, which resolved the urolithiasis risk for the remaining five animals.

New alternatives for minimally invasive management of uroliths: nephroliths.

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.

Removal of ureteral calculi in two geldings via a standing flank approach.

CASE DESCRIPTION: Two geldings, aged 11 and 17 years, were examined for treatment of ureteroliths located approximately 10 cm proximal to the bladder. CLINICAL FINDINGS: Ureteral obstruction was an incidental finding in 1 horse that was referred because of urinary tract obstruction and a cystic calculus. This horse did not have clinical or laboratory evidence of renal failure, although severe hydronephrosis was evident on transabdominal ultrasonography. The second patient had a serum creatinine concentration of 6.3 mg/dL (reference range, 0.8 to 2.2 mg/dL) and mild hydronephrosis of the affected left kidney. TREATMENT AND OUTCOME: In both patients, the obstructed ureter was exteriorized through a flank incision as a standing procedure, and the calculus was crushed and removed with a uterine biopsy forceps introduced through a ureterotomy approximately 25 cm proximal to the calculus. The cystic calculus was removed through a perineal urethrostomy by lithotripsy, piecemeal extraction, and lavage. The horse without azotemia developed pyelonephritis in the affected kidney and was euthanatized because of complications of a nephrectomy 13 months later. In the horse with azotemia, the serum creatinine concentration decreased after surgery, and the horse returned to its intended use. However, it was euthanatized approximately 2 years after surgery because of progressive renal failure, and a large nephrolith was found in the previously unobstructed right kidney. CLINICAL RELEVANCE: The technique used for ureterolith removal was successful in both horses in this report, did not require sophisticated equipment, and could be effective in the early stages of ureteral obstruction as a means of restoring urine flow and renal function. The outcome in the horse with advanced unilateral renal disease without azotemia would suggest that nephrectomy should be considered as a treatment in such patients.

Treatment of ureteral calculus obstruction with laser lithotripsy in an Atlantic bottlenose dolphin (Tursiops truncatus).

An adult female bottlenose dolphin (Tursiops truncatus) presented with acute anorexia secondary to progressive azotemia (blood urea nitrogen = 213 mg/dl, creatinine [Cr] = 9.5 mg/dl) and electrolyte abnormalities (K = 7.4 mEq/L). It was later diagnosed with postrenal obstruction secondary to bilaterally obstructing ureteral calculi seen on ultrasound. Treatment of the obstruction required two endoscopic procedures, cystoscopy for ureteral stent placement and ureteroscopy to perform intracorporeal lithotripsy on the obstructing calculi. Before the first procedure, the dolphin's azotemia was stabilized with aggressive fluid therapy, peritoneal dialysis, and treatment for acidosis. Diuresis subsequent to the fluid therapy enabled passage of the right obstructing urolith. For both endoscopic procedures, the dolphin was placed in left lateral recumbency due to the peritoneal dialysis catheter in the right retroperitoneal region. For the first procedure, a 12-French (Fr) flexible cystoscope was inserted retrograde into the bladder via the urethra, whereupon a calculus was seen obstructing the left ureteral orifice. A 4.8-Fr, 26-cm double-pigtail ureteral stent was placed up the left ureter to relieve the postrenal obstruction. Inadvertent proximal migration of the left ureteral stent occurred during the procedure. However, renal parameters (serum Cr = 5.8, K = 5.4) improved significantly by the next day. For the second procedure, 28 hr later, ureteroscopy was performed to treat the calculus and replace the existing stent with a longer stent. The left ureteral calculus was pulverized into tiny fragments by using a holmium:yttrium-aluminum-garnet laser inserted through a 6.9-Fr semirigid ureteroscope. The migrated stent was visualized in the distal left ureter and replaced with a 90-cm single-pigtail ureteral stent that was sutured exterior to the urogenital slit and removed 3 days later. Renal function normalized over the next several days, and the dolphin recovered over the next 2 mo.

Ultrasound-guided percutaneous antegrade pyelography with computed tomography for the diagnosis of spontaneous partial ureteral rupture in a dog.

A 10-year-old spayed female dalmatian dog developed acute vomiting and abdominal pain. Ultrasound examination of the abdomen showed right hydronephrosis and proximal ureter dilation with mild retroperitoneal free fluid. Computed tomography (CT) of the abdomen confirmed the ultrasonographic findings and revealed, additionally, a right ureteral stone. Spontaneus rupture of the right ureter was confirmed with CT post ultrasound-guided percutaneous antegrade pyelography. Pyeloureteral rupture and the presence of a ureteral stone were confirmed at surgery.

Pyélographie antégrade percutanée guidée par échographie avec tomodensitométrie pour le diagnostic d'une rupture urétrale partielle spontanée chez un chien. Une chienne Dalmatien stérilisée âgée de 10 ans a manifesté des vomissements et de la douleur abdominale aigus. Une échographie de l'abdomen a montré de l'hydronéphrose à droite et une dilatation proximale de l'urètre avec un peu de liquide rétropéritonéal libre. Une tomodensitométrie de l'abdomen a confirmé les résultats de l'échographie et a révélé, en plus, un calcul urétéral droit. Une rupture spontanée de l'urètre droit a été confirmée par tomodensitométrie après une pyélographie antégrade percutanée guidée par échographie. La rupture pyélo-urétérale et la présence de calcul urétéral ont été confirmées à la chirurgie.(Traduit par Isabelle Vallières).

Diagnosis of urolithiasis.

Diagnostic imaging is usually required to determine the presence of urolithiasis. Double-contrast cystography is more accurate than survey radiography and approximately as accurate as ultrasonography. Knowledge of the mineral composition of calculi helps direct appropriate management of urolithiasis, and signalment can help predict composition with about 70% accuracy. In cats, about half of cystic calculi are struvite and half are calcium oxalate; most nephroliths and ureteroliths are calcium oxalate. In female dogs, struvite uroliths are the predominant type found in the bladder. In male dogs, breed plays a strong role in prediction of bladder urolith type. It is difficult to predict the composition of nephroliths and ureteroliths based on signalment alone in dogs. Urinalysis and imaging findings can help in predicting urolith composition, although chemical analysis is necessary for definitive diagnosis.

Evaluation of trends in urolith composition in cats: 5,230 cases (1985-2004).

OBJECTIVE: To determine trends in urolith composition in cats. DESIGN: Retrospective case series. SAMPLE POPULATION: 5,230 uroliths. PROCEDURES: The laboratory database for the Gerald V. Ling Urinary Stone Analysis Laboratory was searched for all urolith submissions from cats from 1985 through 2004. Submission forms were reviewed, and each cat's age, sex, breed, and stone location were recorded. RESULTS: Minerals identified included struvite, calcium oxalate, urates, dried solidified blood, apatite, brushite, cystine, silica, potassium magnesium pyrophosphate, xanthine, and newberyite. During the past 20 years, the ratio of calcium oxalate stones to struvite stones increased significantly. When only the last 3 years of the study period were included, the percentage of struvite stones (44%) was higher than the percentage of calcium oxa-late stones (40%). The most common location for both types of uroliths was the bladder. The number of calcium oxalate-containing calculi in the upper portion of the urinary tract increased significantly during the study period. The number of apatite uroliths declined significantly and that of dried solidified blood stones increased significantly, compared with all other stone types. No significant difference in the number of urate stones was detected. CONCLUSIONS AND CLINICAL RELEVANCE: The increasing proportion of calcium oxalate uroliths was in accordance with findings from other studies and could be a result of alterations in cats' diets. However, the decreased percentage of calcium oxalate calculi and increased percentage of struvite calculi observed in the last 3 years may portend a change in the frequency of this type of urolith.

Retrieval of ureteral calculus using a new method of endoscopic assistance in a cat.

A 9-year-old female spayed domestic short-haired cat presented with ureteral obstruction due to a ureteral calculus 4 cm distal to the renal pelvis. Preoperative creatinine was 844 mmol/L. A novel approach to this condition was utilised whereby a flexible endoscope was passed through a hole made in the renal capsule into the renal pelvis and ureter. The calculus was visualised, and the endoscope was removed. A 1.4 mm flexible grasping forceps was introduced into the proximal ureter through the same hole in the renal capsule and the calculus was removed. The creatinine dropped to 282 micromol/L within 2 weeks of surgery. The cat died of apparently unrelated causes several months after surgery.

Clinical, clinicopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1984-2002).

OBJECTIVE: To determine clinical, clinicopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi. DESIGN: Retrospective study. ANIMALS: 163 client-owned cats. PROCEDURE: Medical records were reviewed, and information on signalment, history, clinical signs, and results of clinicopathologic testing and diagnostic imaging was obtained. RESULTS: The number of cats in which ureterolithiasis was diagnosed each year increased progressively during the study period. Clinical signs tended to be non-specific and included inappetence, vomiting, lethargy, and weight loss. A combination of survey radiography and abdominal ultrasonography revealed ureteral calculi in 66 of 73 (90%) cats in which the diagnosis was confirmed at surgery or necropsy. Ultrasonography revealed that ureteral calculi were causing ureteral obstruction in 143 of 155 (92%) cats. One hundred thirty-four of 162 (83%) cats had azotemia, 84 of 156 (54%) had hyperphosphatemia, and 22 of 152 (14%) had hypercalcemia. Urinary tract infection was documented in 10 of 119 (8%). Fifty-eight of 76 (76%) cats with unilateral ureterolithiasis had azotemia and 33 (43%) had hyperphosphatemia, indicating impairment of renal function in the contralateral kidney or prerenal azotemia. Ultrasonographic imaging of the contralateral kidney in cats with unilateral ureteral calculi suggested that preexisting renal parenchymal disease was common in cats with ureterolithiasis. Ninety-one of 93 (98%) ureteral calculi contained calcium oxalate. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that abdominal imaging should be performed in all cats with chronic nonspecific signs or with acute or chronic renal failure to rule out ureterolithiasis. Preexisting renal disease may be common in cats with ureteral calculi.

Management and outcome of cats with ureteral calculi: 153 cases (1984-2002).

OBJECTIVE: To determine outcome of medical and surgical treatment in cats with ureteral calculi. DESIGN: Retrospective study. ANIMALS: 153 cats. PROCEDURE: Medical records were reviewed. Owners and referring veterinarians were contacted for follow-up information. RESULTS: All cats were initially treated medically before a decision was made to perform surgery. Medical treatment included parenteral administration of fluids and diuretics to promote urine production and passage of the ureteral calculus and supportive treatment for renal failure. Ureteral calculi in the proximal portion of the ureter were typically removed by ureterotomy, whereas ureteral calculi in the distal portion of the ureter were more likely to be removed by partial ureterectomy and ureteroneocystostomy. Ureterotomy could be performed without placement of a nephrostomy tube for postoperative urine diversion. Postoperative complication rate and perioperative mortality rate were 31% and 18%, respectively. The most common postoperative complications were urine leakage and persistent ureteral obstruction after surgery. Chronic renal failure was common at the time of diagnosis and continued after treatment, with serum creatinine concentration remaining greater than the upper reference limit in approximately half the cats. Twelve-month survival rates after medical and surgical treatment were 66% and 91%, respectively, with a number of cats dying of causes related to urinary tract disorders, including ureteral calculus recurrence and worsening of chronic renal failure. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that medical and surgical management of ureteral calculi in cats are associated with high morbidity and mortality rates. Treatment can stabilize renal function, although many surviving cats will continue to have impaired renal function.

Diagnosis and surgical management of ureteral calculi in dogs: 16 cases (1990-2003).

AIMS: To examine the clinical signs, laboratory and radiographic findings, surgical technique, ureterolith composition, and post-operative outcomes in dogs managed surgically for ureterolithiasis to determine whether surgical removal of ureteroliths in dogs resulted in a positive clinical outcome. METHODS: The medical record database of a university veterinary hospital in Pennsylvania, USA, was searched for dogs that underwent surgery to remove obstructive ureteral calculi between 1990 and 2003. Records were reviewed for signalment, clinical history and examination findings, radiographic and laboratory test results, surgical technique, and ureterolith analysis. Follow-up information was obtained from telephone interviews with owners or referring veterinarians, or by reviewing the medical record of subsequent hospital visits. RESULTS: Sixteen dogs were included in this study; ten were neutered females, two intact females and four castrated males. Abdominal radiography revealed ureteral calculi in 14/16 dogs, renal calculi in 8/16, cystic calculi in 8/16, urethral calculi in 1/16, renomegaly in 6/16 and renal mineralisation in 5/16. Ureterolith type included struvite in six dogs, calcium oxalate in five, calcium phosphate in one, and a mix of struvite, calcium phosphate and calcium oxalate in another. Compared to dogs with non-struvite ureteroliths, those with struvite ureteroliths had a higher pre-operative white blood cell (WBC) count (25.6, SD 7 vs 17.6, SD 6 x 103 cells/mul; p=0.046), and were more likely to have a purulent discharge from the ureteral incision noted at the time of surgery (p=0.015). Following discharge, 14/16 dogs were re-evaluated. Median survival time was 904 days (range 2-1,876). Two dogs required additional surgery on the urinary tract. Four dogs died or were euthanised because of azotaemia and clinical signs related to the urinary system or non-specific signs of illness (vomiting, lethargy) at 8, 90, 333 and 904 days post-operatively. CONCLUSIONS: Surgical management of ureteroliths was successful and resulted in good long-term survival in the majority of dogs examined in this small study population. Similar proportions of calcium oxalate and struvite ureteroliths were identified. CLINICAL RELEVANCE: The use of the ureteral surgery may increase as the frequency of diagnosis of ureteroliths in dogs increases.

Ureterolithiasis and papilloma formation in the ureter of a guinea pig.

A 5-year-old guinea pig with suspected urolithiasis was presented for radiology and ultrasound examinations of the abdomen. Radiographically, an irregular-shaped mineral opacity was detected in the area of the urinary bladder. Ultrasonographically, pyelectasia of the right kidney, hydroureter with an ureterolith cranial to a thickened ureter wall close to the ureterovesical junction, and a thickened urinary bladder wall were detected. Histopathologically, the thickened ureter wall was found to be a papilloma. The ureter calculus consisted of 100% calcite.

Laser lithotripsy of a urethral calculus via ischial urethrotomy in a steer.

A steer examined because of obstructive urolithiasis and urethral rupture underwent laser lithotripsy, using a chromium-thulium-holmium:yttrium-aluminum-garnet (Ho:YAG) laser inserted through an ischial urethrotomy. Procedures were performed with caudal epidural anesthesia. Six months after surgery, the urethra was patent with no clinical evidence of urethral stricture or fistula. Ischial urethrotomy provided rapid access to the bladder for catheterization and to the obstructive urolith for lithotripsy. Laser lithotripsy was a rapid and effective means of urolith removal in this steer.

Urolithiasis in cynomolgus monkey (Macaca fascicularis): a case report.

Only a few cases of urinary calculi have been reported in cynomolgus monkeys. The adult male Macaca fascicularis presented here had two calculi, both of which were 100% calcium carbonate. Similar calculi occur in humans.

Ureterotomy for removal of two ureteroliths in a parrot.

A 21-year-old male double-yellowheaded Amazon parrot was referred because of possible urolithiasis. The bird had strained to void since it was young, and recently, signs of depression and inappetence had appeared. Radiography revealed 2 mineralized opacities in the left caudal portion of the celomic cavity. A left lateral celiotomy revealed that the left ureter was dilated and contained a calculus, which was later determined to be composed of monosodium uric acid crystals and proteinaceous material. The second mineralized mass could not be located at that time, but was detected in the caudal aspect of the celomic cavity after surgery by use of radiography. Manual attempts to maneuver the uterolith from the ureter through the cloaca were unsuccessful. Five days after the initial surgery, the uterolith was removed by cloacotomy and ventral midline laparotomy. Excretory urography performed 10 and 31 days after surgery revealed that the left ureter was homogeneously opacified and gradually decreased to 3 to 6 mm in diameter. The bird remained healthy and seemed to strain less severely during voiding. Nonspecific signs associated with ureteroliths may result in delay in diagnosis. Surgical removal of ureteroliths may be an effective treatment for this uncommon condition, but it is complicated by certain anatomic features of birds and may result in ureteral stricture.

Chronic renal failure associated with nephrolithiasis, ureterolithiasis, and renal dysplasia in a 2-year-old quarter horse gelding.

A 2-year-old quarter horse gelding presented for evaluation of polyuria and polydipsia. Azotemia was detected on serum chemistry profile. Small, misshapen, hyperechoic kidneys with decreased corticomedullary demarcation, hydronephrosis, and a right nephrolith were noted ultrasonographically. The diagnosis of end-stage kidney disease and dysplasia was made histopathologically using ultrasound-guided biopsy. Two ureteroliths were found in the right ureter via cystoscopy, and a nephrolith was seen in the right kidney at necropsy. Clinical, ultrasonographic, and pathologic features of equine urolithiasis and renal dysplasia are discussed.