The most common types of uroliths larger than 1 mm are readily visible and accurately measured in an in vitro setting mimicking the canine abdomen using digital radiography

Abdominal radiography is an important diagnostic to detect uroliths. Cystine and urate uroliths were historically characterized as nonmineral opaque on survey radiographs. However, recent research and clinical observations indicate that pure urate and cystine uroliths may be detected with digital radiography. The primary purpose of this prospective, in vitro, diagnostic accuracy study was to determine the sensitivity of digital radiography in detecting cystoliths of varying size and composition. Forty canine uroliths of pure composition (10 each of calcium oxalate, struvite, cystine, and urate), acquired from Minnesota Urolith Center and ranging from 1 to 10 mm, were placed in phantoms of three various sizes and radiographed. The radiographs, including three sets of each urolith separately, were evaluated by three blinded radiologists on two separate occasions. Evaluation included presence or absence of urolith, number of uroliths, and maximum diameter of the urolith(s). For all four types of uroliths and all readers, the specificity and PPV were 100% with an associated very high sensitivity (94.4%-98.9%) and NPV (94.8%-98.9%). Calcium oxalate uroliths were the most accurately measured and struvite were the least accurately measured when compared with the gross measurement. Smaller uroliths were more accurately measured than larger uroliths. Uroliths placed in smaller bladder phantoms were more accurately measured than in larger bladder phantoms. Though accurate measurement of uroliths is complicated by and dependent on numerous variables, our results reveal that urate and cystine uroliths are visualized on digital radiography making them a relevant differential diagnosis when seen clinically.

Comparison of radiographic methods for detecting radiolucent uroliths in dogs

The purpose of this study was to evaluate and compare positive cystography techniques at 5%, 10%, and 20%, as well as three different double-contrast protocols for detecting radiolucent uroliths with a diameter of less than 3.0 mm in dogs. Six cadavers were used, one was selected at random to represent the negative control, and the others were submitted to urolith implantation in the bladder by urethral catheter. Three radiology professionals blindly accessed ventrodorsal and -lateral projections of each test. Contrast at 20% showed greater diagnostic sensitivity, but with greater difficulty identifying the number and size of the uroliths. Consequently, double-contrast techniques are better and should be used for diagnostic and therapeutic planning. Sensitivity and specificity tests demonstrated that positive 5% cystography and different concentrations of double contrast obtained better results in terms of sensitivity and specificity. However, due to the presence of a greater amount of artifacts in the 5% cystography, it is suggested that double contrast is used for this purpose, especially with the removal of contrast excess (protocol 2).

Präpubische Urethrostomie bei einem Wiesenauer Minischwein mit Urolithiasis

Ein 10-jähriges kastriertes, männliches Minischwein wurde aufgrund eines Tenesmus vesicae mit Anurie vorgestellt. Begleitsymptom war eine Tachypnoe. Röntgenologisch waren zahlreiche Harnsteine in Blase und Urethra nachweisbar. Über die Harnröhre konnte nicht katheterisiert werden, sodass eine Notfallzystostomie mit Einlegen eines Ballonkatheters durchgeführt wurde. Trotz Blasenspülung gelang es nicht die Harnröhrensteine so auszuspülen. Deswegen wurde ein präpubisches Urethrostoma angelegt. Das Tier erholte sich vollständig und setzt seither problemlos Urin über die urethrale Fistel ab. Prophylaktische Maßnahmen der Urolithiasis beinhalten unter anderem eine ausreichende Wasseraufnahme, eine ausgewogene Fütterung und balancierte Futterzusammensetzung sowie die Gewährleistung eines physiologischen Urin-pH-Werts.

Efficacy of medical dissolution for suspected struvite cystoliths in dogs

Background

Medical dissolution of struvite uroliths in dogs is commonly recommended, but data on success rates and complications are limited.

Objectives

To evaluate the efficacy of medical dissolution for suspected struvite cystoliths in dogs.

Animals

Fifty client‐owned dogs fed a therapeutic dissolution diet, with or without administration of antimicrobials, for treatment of suspected struvite cystoliths.

Methods

Single institution, retrospective case series. Medical records were reviewed for dogs with at least 1 follow‐up visit. Dissolution success, complications, and possible predictors of success were evaluated.

Results

Full dissolution of cystoliths was achieved in 58% (29/50) of dogs within a median of 35 days (range, 13‐167). Of 21 dogs without success, 7 each had partial dissolution, no dissolution, or undetermined outcome. Uroliths containing >10% nonstruvite mineral were common in the nonsuccess group (11/16 analyzed). Maximum urolith diameter, number of uroliths, and baseline urine pH did not differ significantly between dogs with and without success. Dissolution was more likely in dogs receiving antimicrobial therapy (OR = 16.3, 95% confidence interval 1.9‐787.4, P = .002). Adverse events occurred in 9 dogs (18%); urethral obstructions were the most common, but 3 of 4 dogs with this complication were obstructed on presentation, before trial initiation.

Conclusions and Clinical Importance

Results support a medical dissolution trial for dogs with suspected struvite cystoliths. If no reduction in urolith size or number occurs by 1 month, a nonstruvite composition is likely, and alternative interventions should be considered. Dogs presenting with urethral obstructions should not be considered candidates for medical dissolution.

Diagnostic Imaging of the Reptile Urinary System

Reptiles can develop various diseases of the urinary tract, including, but not exclusively, urolithiasis, gout, acute and chronic kidney injury, and secondary renal hyperparathyroidism. Diagnostic imaging is instrumental in differentiating and diagnosing these ailments. This article describes the current diagnostic imaging approaches used in reptile medicine for evaluation of urinary tract disease. The use of radiographs, ultrasonography, computed tomography, MRI, and endoscopy is discussed and compared for the evaluation of urinary tract disease in reptiles.

Efficacy of two commercially available, low-magnesium, urine-acidifying dry foods for the dissolution of struvite uroliths in cats

OBJECTIVE

To compare the efficacy and safety of using 2 commercially available, low-magnesium, urine-acidifying dry foods to dissolve sterile struvite uroliths in cats.

DESIGN

Prospective, multicenter, randomized clinical trial .

SAMPLE

37 cats with presumed struvite uroliths.

PROCEDURES

Cats were randomly assigned to be fed 1 of 2 low-magnesium, urine-acidifying dry foods (food A or B). For each cat, physical examination, urinalysis, and abdominal radiography were performed weekly to assess treatment response.

RESULTS

32 cats had complete urolith dissolution. Mean ± SD times for a 50% reduction in urolith size (0.69 ± 0.1 weeks) and complete urolith dissolution (13.0 ± 2.6 days) were significantly shorter for cats fed food A, compared with those (1.75 ± 0.27 weeks and 27.0 ± 2.6 days, respectively) for cats fed food B. At study termination, mean ± SD urine pH (6.083 ± 0.105) for cats fed food A was lower than that (6.431 ± 0.109) for cats fed food B. In 5 cats, uroliths did not dissolve and were subsequently determined to be composed of 100% ammonium urate (n = 4) or 100% calcium oxalate (1). Adverse events associated with diet were not observed in any of the cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that dietary dissolution is safe and effective for eradication of sterile struvite uroliths in cats. Cats fed food A had faster urolith dissolution than did cats fed food B. Lack of a reduction in urolith size at 2 weeks after diet initiation was indicative of misdiagnosis or noncompliance.