Effects of hydrochlorothiazide and diet in dogs with calcium oxalate urolithiasis

OBJECTIVE: To determine whether hydrochlorothiazide (HCTZ) reduces urinary calcium excretion in dogs with calcium oxalate urolithiasis. DESIGN: Original study. ANIMALS: 8 dogs with calcium oxalate urolithiasis. PROCEDURE: 4 treatment protocols were evaluated in each dog (a low calcium, low protein diet designed to prevent calcium oxalate urolith formation with and without administration of HCTZ [2 mg/kg (0.9 mg/lb) of body weight, PO, q 12 h] and a maintenance diet with higher quantities of protein and calcium with and without administration of HCTZ). At the end of each 2-week treatment period, 24-hour urine samples were collected. Blood samples were collected during the midpoint of each urine collection period. Analysis of variance was performed to evaluate the effects of HCTZ and diet on urine and serum analytes. RESULTS: Hydrochlorothiazide significantly decreased urine calcium and potassium concentration and excretion. Hydrochlorothiazide also significantly decreased serum potassium concentration. Compared with the maintenance diet, the urolith prevention diet significantly decreased urine calcium and oxalic acid concentration and excretion. Dogs consuming the urolith prevention diet had significantly lower serum concentrations of albumin and urea nitrogen. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of HCTZ decreased urine calcium excretion in dogs with a history of calcium oxalate urolith formation. The greatest reduction in urine calcium concentration and excretion was achieved when dogs received HCTZ and the urolith prevention diet. Results of this study suggest that the hypocalciuric effect of HCTZ will minimize recurrence of calcium oxalate urolith formation in dogs; however, long-term controlled clinical trials are needed to confirm the safety and effectiveness of HCTZ.     

Calcium urolithiasis in two dogs with parathyroid adenomas

Primary hyperparathyroidism resulted in calcium urolith formation and calcium nephropathy in 2 dogs. Uroliths composed of calcium phosphate were surgically removed from the bladder of one dog 3 months after surgical removal of a parathyroid adenoma. Five years later, hypercalcemia and urolithiasis had not recurred. In a second dog, calcium oxalate renal and bladder uroliths remained unchanged in size at 11 months after removal of a parathyroid adenoma. The possibility of primary hyperparathyroidism should be considered in any dog with calcium urolithiasis.     

Patient and environmental factors associated with calcium oxalate urolithiasis in dogs

OBJECTIVE: To test the hypothesis that breed, age, sex, body condition, and environment are risk factors for development of calcium oxalate uroliths in dogs. DESIGN: Case-control study. ANIMALS: 1,074 dogs that formed calcium oxalate uroliths and 1,724 control dogs that did not have uroliths. PROCEDURE: A validated multiple-choice questionnaire was designed to collect information from veterinarians and owners within 1 year of the date of urolith detection concerning signalment and environment of the dogs. Univariate and multivariate analyses were performed to calculate odds ratios to assess whether breed, age, sex, body condition, and environment were risk factors for calcium oxalate urolith formation. RESULTS: Middle-aged (8- to 12-year-old) castrated male dogs had increased risk for formation of calcium oxalate uroliths. Urolith formation was also associated with increasing age. Dogs of certain breeds, including Miniature and Standard Schnauzer, Lhasa Apso, Yorkshire Terrier, Bichon Frise, Shih Tzu, and Miniature and Toy Poodle, had increased risk for developing calcium oxalate uroliths. Overweight dogs also had increased risk. CONCLUSIONS AND CLINICAL RELEVANCE: Knowledge of patient and environmental risk factors for development of calcium oxalate uroliths may facilitate development of surveillance strategies that result in earlier detection of this disease. Modification of environmental factors and body weight may minimize calcium oxalate urolith formation and recurrence.     

Comparison of three techniques for the diagnosis of urinary tract infections in dogs with urolithiasis

OBJECTIVES: To identify an appropriate sampling technique(s) to accurately detect the bacteria causing urinary tract infections in dogs with urolithiasis. METHODS: Twenty-one dogs with urolithiasis were included in the study. Three types of samples were taken from each dog. Urine was collected by cystocentesis, and a urinary bladder mucosal biopsy and urolith were retrieved during cystotomy. The samples were then cultured on blood agar and MacConkey's agar to identify the bacteria associated with urinary tract infections. RESULTS: Bacterial urinary tract infection was found in 16 cases (76.19 per cent). The most prevalent bacteria found to cause urinary tract infection were Escherichia coli (n=7), followed by coagulase-positive Staphylococcus species (n=4), Klebsiella pneumoniae (n=2), Pseudomonas aeruginosa (n=2) and Proteus mirabilis (n=1). In the case of a positive urine culture, the same bacteria were also cultured from the urinary bladder mucosal biopsy alone or from both the urinary bladder mucosal biopsy and urolith. However, in the case of a negative urine culture, bacteria were found to be present in the urinary bladder mucosal biopsy or urolith cultures in 23.81 per cent of dogs. The uroliths that gave positive culture results were either infection-induced uroliths composed of struvite and calcium carbonate phosphate, ammonium acid urate only or metabolic uroliths composed of calcium oxalate and calcium phosphate, or calcium phosphate only. All the uroliths that gave negative culture results were metabolic uroliths composed of calcium oxalate and/or calcium phosphate, and uric acid and calcium phosphate. CLINICAL SIGNIFICANCE: When the culture from the urine obtained by cystocentesis is negative, cultures of urinary bladder mucosal biopsy and urolith are recommended in dogs with urolithiasis in order to accurately assess the microbiological status of the urinary tract.     

长期饲喂高鸡肝饲粮所致犬尿结石成分的分析研究

对１例长期饲喂高鸡肝饲粮所致犬尿结石样品,利用化学定性、Ｘ－射线衍射、扫描电镜观察与能谱分析等手段进行化学组成和显微形态分析。结果表明,样品中棺盖状晶体、蜂窝状颗粒及某些形状的颗粒均以磷酸铵镁为主要组成成分,形状不甚清晰的小粒状颗粒以磷酸钙为主要成分。另外还对数份饲喂高鸡肝饲粮之犬尿沉渣进行光学显微镜观察,发现有大量磷酸盐及少量碳酸钙。作者对尿石的形成及尿沉渣与尿石的关系进行了简要讨论,并对宠物犬尿石症的预防提出了建议     

Evaluation of 21 426 feline bladder urolith submissions to the Canadian Veterinary Urolith Centre (1998–2014)

This study reports emerging trends in feline urolithiasis in Canada during the past 16.8 y, evaluates associations of breed and gender with urolith types, and reports on feline submissions from outside of Canada. Struvite and calcium oxalate uroliths comprised > 90% of all uroliths submitted. In cats, oxalate submissions outnumbered struvite submissions from Canada, Hong Kong, Denmark, and the United Arab Emirates, while Australian struvite submissions outnumbered calcium oxalate submissions. In Canada, the majority of urolith submissions were from domestic cats followed by Himalayan, Persian, and Siamese cats. Males were more likely to form calcium oxalate uroliths and females were more likely to develop struvite uroliths. Compared to domestic short-haired cats, Tonkinese, Burmese, Devon rex, Himalayan, Persian, and Siamese cats were significantly associated with calcium oxalate urolith submission. Egyptian mau, Birman, ocicat, and Siamese breeds were over-represented amongst urate submissions.     

Associations between dietary factors in canned food and formation of calcium oxalate uroliths in dogs

OBJECTIVE: To identify dietary factors in commercially available canned foods associated with the development of calcium oxalate (CaOx) uroliths in dogs. ANIMALS: 117 dogs with CaOx uroliths and 174 dogs without urinary tract disease. PROCEDURE: Case dogs were those that developed CaOx uroliths submitted to the Minnesota Urolith Center for quantitative analysis between 1990 and 1992 while fed a commercially available canned diet. Control dogs were those without urinary tract disease evaluated at the same veterinary hospital just prior to or immediately after each case dog. A content-validated multiple-choice questionnaire was mailed to each owner of case and control dogs with the permission of the primary care veterinarian. Univariate and multivariate logistic regressions for each dietary component were performed to test the hypothesis that a given factor was associated with CaOx urolith formation. RESULTS: Canned foods with the highest amount of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, or moisture were associated with a decreased risk of CaOx urolith formation, compared with diets with the lowest amounts. In contrast, canned diets with the highest amount of carbohydrate were associated with an increased risk of CaOx urolith formation. CONCLUSIONS AND CLINICAL RELEVANCE: Feeding canned diets formulated to contain high amounts of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, and moisture and a low amount of carbohydrate may minimize the risk of CaOx urolith formation in dogs.     

Mixed urolith (struvite and calcium oxalate) in a ferret (Mustela putorius furo)

Urolithiasis has been reported in veterinary literature in some species of the Mustelidae family, including ferrets. In this species, the most common form of urolithiasis is that caused by struvite. The current study examined the case of mixed urolith in an 8-month-old female ferret (Mustela putorius furo) with antecedents of strangury and hematuria. A cystotomy was carried out to remove the urolith, which had a rough surface and a homogeneously porous interior and was formed by a mixture of struvite (60%) and calcium oxalate dehydrated (40%).     

In vitro prediction of canine urolith mineral composition using computed tomographic mean beam attenuation measurements

Determination of urolith mineral composition is critical for management of urolithiasis in dogs and cats. Using computed tomography, urolith physical density, and hence chemical composition, can be quantified using mean beam attenuation measurements (Hounsfield units; HU). This study was designed to establish in vitro reference ranges for three types of compositionally pure uroliths retrieved from dogs. Sixty-six canine uroliths (22 uric acid, 21 calcium oxalate, 14 struvite, nine mixed or compound) were placed in a phantom array. Uroliths were scanned at 120 kVp, 200 mA, and 80 kVp, 200 mA. The region of interest (ROI) for mean HU calculation was determined using two techniques, and reference ranges were calculated for each kVp using either ROI technique. HU for urolith types of pure composition were statistically different (Wilcoxon's two-sample test, P < 0.0083 [Bonferonni correction with six comparisons for total P < 0.05]) using both ROI techniques at either kVp. Struvite uroliths were not statistically different from mixed or compound uroliths. The accuracy for determination of composition of pure uroliths ranged from 86% to 93%; the prediction accuracy for each urolith mineral type and for all uroliths in general was highest when the ROI was hand-drawn just within the visible urolith border at 80 kVp. Technique of ROI determination and kVp that yielded the highest sensitivity, specificity, and positive and negative predictive values varied for each urolith type. Therefore, in this study, HU could be used to differentiate three types of uroliths of pure mineral composition in vitro. Further studies are needed to determine the predictive value of HU in vivo.     

Effects of diet on urine composition of cats with calcium oxalate urolithiasis

Ten client-owned cats with calcium oxalate (CaOx) urolithiasis were evaluated to determine the effect of diet on urine CaOx saturation. Two dietary treatments were evaluated in each cat: the diet consumed just prior to urolith detection and a canned diet formulated to prevent CaOx uroliths. This study revealed that hypercalciuria is a consistent abnormality in cats with CaOx urolith formation. When urolith-forming cats consumed a diet formulated to prevent urolith formation, activity product ratios for CaOx (which estimate the degree to which urine is saturated with CaOx) were significantly lower. These results suggest that consumption of an appropriately formulated urolith-prevention diet will reduce recurrence of CaOx urolithiasis.     

Association between dietary factors and calcium oxalate and magnesium ammonium phosphate urolithiasis in cats.

OBJECTIVE: To identify dietary factors associated with the increase in occurrence of calcium oxalate (CaOx) uroliths and the decrease in occurrence of magnesium ammonium phosphate (MAP) uroliths in cats. DESIGN: Case-control study. ANIMALS: 173 cats with CaOx uroliths, 290 cats with MAP uroliths, and 827 cats without any urinary tract diseases. PROCEDURE: Univariate and multivariate logistic regression were performed. RESULTS: Cats fed diets low in sodium or potassium or formulated to maximize urine acidity had an increased risk of developing CaOx uroliths but a decreased risk of developing MAP uroliths. Additionally, compared with the lowest contents, diets with the highest moisture or protein contents and with moderate magnesium, phosphorus, or calcium contents were associated with decreased risk of CaOx urolith formation. In contrast, diets with moderate fat or carbohydrate contents were associated with increased risk of CaOx urolith formation. Diets with the highest magnesium, phosphorus, calcium, chloride, or fiber contents and moderate protein content were associated with increased risk of MAP urolith formation. On the other hand, diets with the highest fat content were associated with decreased risk of MAP urolith formation. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that diets formulated to contain higher protein, sodium, potassium, moisture, calcium, phosphorus, and magnesium contents and with decreased urine acidifying potential may minimize formation of CaOx uroliths in cats. Diets formulated to contain higher fat content and lower protein and potassium contents and with increased urine acidifying potential may minimize formation of MAP uroliths.     

犬膀胱结石的化学成分分析研究

应用化学定性分析、X 射线衍射物相分析、扫描电镜观察与X 射线能谱分析等方法 ,对 3例取自临床病例的犬膀胱结石样品进行了化学成分分析。结果表明 ,3例结石的化学成分分别为磷酸钙、磷酸铵镁和混合性结石。对 3种结石晶体的生成机理进行了讨论 ,分析了犬膀胱结石的发病原因。     

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.     

Effects of dietary ammonium chloride and variations in calcium to phosphorus ratio on silica urolithiasis in sheep.

Ammonium chloride was added to diets varying in Ca content to evaluate its potential in preventing silica urolith formation in sheep. A 2 x 2 factorial experiment involved wether lambs with ad libitum access to a diet of 50% grass hay and 50% ground oats plus supplement. The basal diet contained on a DM basis 3.3% SiO2, .31% Ca, .22% P, 11.6% CP, and 26% ADF. Treatments (38 to 39 lambs/treatment) consisted of a control (C), limestone to increase dietary calcium to .6% (L), 1% ammonium chloride (A), and L + A (LA). After a 118-d experimental period, siliceous kidney deposits were found only in C and L, with silica making up 93% to 95% of the urolithic ash. Urolith incidences were 13% (C) and 18% (L), respectively. The lack of urolith development in lambs fed A and LA (ammonium chloride effect, P less than .01) and a trend toward a lower urolith incidence in C vs L (P less than .02) support the hypothesis that acid-forming effects of the diet and a reduction in the dietary Ca to P ratio reduce silica urolith formation.     

Holmium:YAG Laser Lithotripsy for Urolithiasis in Horses

Background: Laser lithotripsy has been used as an alternative to surgical removal of uroliths.
Objective: To describe the procedure and efficacy of laser lithotripsy for removal of lower urinary tract uroliths in horses. Additionally, the ultrastructure and the differences in mineralogy and microstructure from 1 successful and 1 unsuccessful laser lithotripsy case are described.
Animals: Six client-owned horses with 7 episodes of naturally occurring urocystoliths, urethroliths, or both.
Methods: Retrospective study of all horses treated between 2006 and 2008 by laser lithotripsy. All horses were sedated followed by laser lithotripsy. Quantitative urolith analysis was performed in all cases. Ultrastructure and microstructure analyses were performed on uroliths from 2 horses.
Results: Procedural success was achieved in 5 of 7 laser lithotripsy procedures. No complications occurred as a result of laser lithotripsy. One horse developed uroabdomen likely as a result of manual lithotrite disruption of the bladder after failure of laser lithotripsy. There were differences in microstructure between 1 urolith that was successfully fragmented by laser lithotripsy and 1 urolith that was resistant to laser fragmentation.
Conclusions and Clinical Importance: Laser lithotripsy is an effective procedure for removal of some urocystoliths, urethroliths, or both in horses.     

Holmium: YAG laser lithotripsy for urolithiasis in dogs

BACKGROUND: Laser lithotripsy has been used as an alternative to surgical removal of uroliths in a number of species. OBJECTIVES: To determine the effectiveness of laser lithotripsy for removing urocystoliths, urethroliths, or both in dogs, and to determine the influence of dog (chronological order of lithotripsy, endoscope type, sex, body weight) and urolith (total urolith and urocystolith number, presence or absence of urethroliths, largest urolith dimension, and urolith composition) factors on outcome. ANIMALS: Twenty-five client-owned dogs with urocystoliths, urethroliths, or both were included. Male dogs were required to weigh > or =6.8 kg. METHODS: A single-arm prospective clinical trial. Laser lithotripsy was performed under general anesthesia. Main outcomes included procedure success and lithotripsy time. Predictors of procedure success and lithotripsy time were selected using logistic and linear regression modeling, respectively. RESULTS: The procedure was successful in 21 of 25 dogs. The procedure was successful more often and in less time in female spayed than in male neutered dogs. Sex was identified as a predictor of success. Univariable analysis showed that sex, endoscope type, and chronological order in which the dog received lithotripsy were significantly associated with lithotripsy time. Stepwise linear regression modeling identified sex, body weight, >10 uroliths, and largest urolith dimension as predictors of lithotripsy time. CONCLUSIONS AND CLINICAL IMPORTANCE: Laser lithotripsy is an effective procedure for the removal of urocystoliths, urethroliths, or both with rare important adverse effects and some limitations in male dogs.     

Parainguinal laparocystotomy for urolith removal in geldings

OBJECTIVE: To describe parainguinal laparocystotomy for urolith removal and to report outcome. STUDY DESIGN: Prospective clinical study. ANIMALS: Ten geldings with uroliths. METHODS: Signalment, number, size, type of uroliths, surgical technique, and complications were recorded. Long-term follow-up was obtained by telephone interviews with the client and/or examination by the referring veterinarian. RESULTS: Cystic calculi, 3-9 cm in diameter, were removed by parainguinal laparocystotomy. Mean surgical time was 59 minutes (range, 40-100 minutes). With this approach, ligation of the pudendal or superficial epigastric vessels was not needed. Serous incisional drainage resolved without treatment in 3 horses and 2 horses developed moderate-to-severe incisional swelling. On long-term follow-up (mean, 52 months; range, 11-82 months) for 9 horses, owners reported no recurrence of clinical signs associated with cystic calculi. CONCLUSIONS: Parainguinal laparotomy represents a satisfactory alternative approach to the apex of the bladder for urolith removal. CLINICAL RELEVANCE: Parainguinal laparocystotomy avoids the pudendal and superficial epigastric blood vessels that are encountered when performing median or paramedian laparocystotomy in geldings. This approach minimizes dead space by avoiding the reflection of the prepuce in paramedian or median approaches.     

Effects of chlorothiazide on urinary excretion of calcium in clinically normal dogs.

Administration of thiazide diuretics has been recommended to prevent calcium oxalate urolith development in dogs. To evaluate the effects of thiazide diuretics in dogs, 24-hour urine excretion of calcium was measured in 6 clinically normal Beagles after administration of chlorothiazide (CTZ) for 2 weeks, administration of CTZ for 10 weeks, and administration of calcium carbonate and CTZ for 2 weeks. Compared with baseline values, 24-hour urine calcium excretion did not decrease after CTZ administration. When CTZ was given at a high dosage (130 mg/kg of body weight), urinary calcium excretion was significantly (P < 0.04) higher than baseline values. Based on these observations, we do not recommend CTZ for treatment or prevention of canine calcium oxalate urolithiasis.     

In vitro evaluation of canine and feline calcium oxalate urolith fragility via shock wave lithotripsy

OBJECTIVE: To test the hypothesis that feline calcium oxalate uroliths are intrinsically more resistant to comminution via shock wave lithotripsy (SWL) than canine calcium oxalate uroliths through comparison of the fragility of canine and feline uroliths in a quantitative in vitro test system. SAMPLE POPULATION: Calcium oxalate uroliths (previously obtained from dogs and cats) were matched by size and mineral composition to create 7 pairs of uroliths (1 canine and 1 feline urolith/pair). PROCEDURE: Uroliths were treated in vitro with 100 shock waves (20 kV; 1 Hz) by use of an electrohydraulic lithotripter. Urolith fragmentation was quantitatively assessed via determination of the percentage increase in projected area (calculated from the digital image area of each urolith before and after SWL). RESULTS: After SWL, canine uroliths (n = 7) fragmented to produce a mean +/- SD increase in image area of 238 +/- 104%, whereas feline uroliths (7) underwent significantly less fragmentation (mean image area increase of 78 +/- 97%). The post-SWL increase in fragment image area in 4 of 7 feline uroliths was < 50%, whereas it was > 150% in 6 of 7 canine uroliths. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that feline calcium oxalate uroliths are less susceptible to fragmentation via SWL than canine calcium oxalate uroliths. In some cats, SWL may not be efficacious for fragmentation of calcium oxalate nephroliths or ureteroliths because the high numbers of shock waves required to adequately fragment the uroliths may cause renal injury.     

Canine urolithiasis: a look at over 16 000 urolith submissions to the Canadian Veterinary Urolith Centre from February 1998 to April 2003

The purpose of this study was to report on the age, sex, breed, and mineral composition of 16 647 canine bladder uroliths submitted to the Canadian Veterinary Urolith Centre between February 1998 and April 2003. Each urolith submission was accompanied by a questionnaire. Of the submissions, approximately 43.8% were struvite and 41.5% oxalate. Struvite uroliths were most common in female dogs. Mixed breed dogs predominated, followed by the shih tzu, bichon frise, miniature schnauzer, Lhasa apso, and Yorkshire terrier. Oxalate uroliths were most common in males and in the miniature schnauzer, bichon frise, Lhasa apso, shih tzu, and Yorkshire terrier. Urate uroliths were most common in male Dalmations. Other urolith types, including cystine, xanthine, silica, and calcium phosphate, were less commonly reported. A review of risk factors for the various uroliths is presented, along with some recommendations for treatment and prevention.