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- Author or Editor: Jodi L. Westropp x
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Objective—To determine the mineral composition of calculi, anatomic locations of the calculi, and findings of urinalysis and bacteriologic culture of urine and calculi in guinea pigs with urolithiasis.
Animals—127 guinea pigs.
Procedures—Records of urinary calculi that had been submitted to the University of California Stone Laboratory from 1985 through 2003 were reviewed. In addition, submissions of urinary calculi for evaluation by the laboratory were prospectively solicited from 2004 through 2007. Prospectively obtained calculi were accompanied by a urine sample for urinalysis and bacteriologic culture and a completed questionnaire. All calculi were analyzed by use of polarized light microscopy and infrared spectroscopy. A subset of calculi was examined by means of x-ray diffractometry (XRD).
Results—83% (43/52) of calculi from the laboratory database and 93% (70/75) of calculi that were prospectively solicited were composed of 100% calcium carbonate. Analysis via XRD confirmed that 5 of 6 calculi from a subset that had the greatest gross morphologic variation were composed of 100% calcite. Although many guinea pigs had received anti-microbials before bacteriologic cultures of urine were performed, Corynebacterium renale was isolated from 5 urine samples.
Conclusions and Clinical Relevance—Contrary to findings of other studies, urinary calculi analyzed for the present study were most commonly composed of 100% calcium carbonate, and infrared spectroscopy or XRD was necessary to differentiate this mineral from others. Treatments, including diet and husbandry practices, should be developed to help prevent development of calcium carbonate calculi in guinea pigs.
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 sig-nificantly 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 fre-quency of this type of urolith.
Objective—To identify clinical features of Corynebacterium urealyticum urinary tract infection in dogs and cats and antimicrobial susceptibility patterns of C urealyticum isolates.
Animals—5 dogs and 2 cats.
Procedure—Medical records of dogs and cats for which C urealyticum was isolated from urine samples were reviewed. Isolates from clinical cases, along with previously lyophilized unsubtyped isolates of Corynebacterium spp collected between 1977 and 1995, were examined and, if subtyped as C urealyticum, tested for antimicrobial susceptibility.
Results—Signalment of infected animals was variable. Prior micturition disorders were common, and all animals had signs of lower urinary tract disease at the time C urealyticum infection was diagnosed. Median urine pH was 8.0; WBCs and bacteria were variably seen in urine sediment. In vitro antimicrobial susceptibility testing of 14 C urealyticum isolates revealed that all were susceptible or had intermediate susceptibility to chloramphenicol, tetracycline, and vancomycin and most were susceptible to enrofloxacin. Thickening of the bladder wall and accumulation of sediment were common ultrasonographic findings. Contrast radiography or cystoscopy revealed findings consistent with encrusting cystitis in 3 dogs. Infection resolved in 2 dogs following surgical debridement of bladder plaques and antimicrobial administration. In 2 other dogs and 1 cat treated with antimicrobials, infection with C urealyticum resolved, but urinary tract infection with a different bacterial species developed.
Conclusions and Clinical Relevance—Results suggest that preexisting urinary tract disorders are common in dogs and cats with C urealyticum infection. Treatment with appropriate antimicrobials in combination with surgical debridement might eliminate C urealyticum infection. (J Am Vet Med Assoc 2005;226:1676–1680)
Case Description—An 8-month-old castrated male mixed-breed dog was evaluated because of hematuria, stranguria, and dysuria of approximately 2 weeks’ duration that developed immediately following elective castration.
Clinical Findings—Results of physical examination, ultrasonography, retrograde double-contrast cystourethrography, and urethroscopy were consistent with a traumatic urethral stricture immediately proximal to the os penis resulting in a partial obstruction of urine outflow. Results of ultrasonographic examination of abdominal organs were considered normal. Digital radiography revealed no evidence of calculi.
Treatment and Outcome—Balloon dilation of the urethral stricture was performed and was followed by 2 bougienage procedures during the subsequent 2 weeks when clinical signs returned. The owners declined scrotal urethrostomy, and a self-expanding, covered nitinol stent was placed approximately 3 weeks after the initial evaluation, resulting in amelioration of clinical signs. Results of follow-up urethroscopy and contrast cystourethrography 1 year after stent placement revealed a statically positioned, patent urethral stent, although a small number of polypoid mucosal structures were identified distal to the stent and 1 small structure consistent with tissue ingrowth into the stent was identified.
Clinical Relevance—Placement of a covered nitinol stent resulted in long-term resolution of clinical signs associated with traumatic stricture of the penile urethra in this young dog. Because the os penis in dogs limits radial expansion of the urethra, its presence may limit the use of stents in this location.
Objective—To evaluate the in vivo response of α2-adrenoceptors to medetomidine administration in cats with feline idiopathic cystitis (FIC) during periods of stress and after environmental enrichment.
Animals—13 cats with FIC and 12 healthy cats.
Procedures—Cats were subjected to an acute-onset moderate stressor for 8 days. After stress, 20 μg of medetomidine/kg was administered IM on days 1, 3, and 8. Heart rate, blood pressure, pupil diameter, respiratory rate, and level of sedation were evaluated before and after administration of the drug. After day 8, cats were moved to an enriched environment, and tests were repeated on day 35.
Results—Heart rate decreased and pupil diameter increased significantly after medetomidine administration in healthy cats, compared with cats with FIC. Cats with FIC had significantly lower respiratory rates. No significant differences in blood pressure or sedation level were found.
Conclusions and Clinical Relevance—Increased plasma catecholamine concentrations during the enrichment phase, which have been reported elsewhere, may have contributed to the differences in α2-adrenoceptor responses detected in cats with FIC.
Objective—To compare effects of isoflurane and propofol on the cystometrogram and urethral pressure profile (UPP) in healthy female cats.
Animals—6 healthy female cats.
Procedures—Cats were anesthetized, and a consistent plane of anesthesia was maintained with low and high doses of isoflurane and propofol. A 6-F double-lumen urinary catheter was placed aseptically in the urethra for cystometrogram and UPP measurements. Threshold pressure and volume were recorded for cystometrograms. Maximum urethral pressure for smooth and skeletal muscle portions of the urethra, maximum urethral closure pressure, and functional profile length were measured during each UPP measurement. Heart rate and respiratory rate were recorded.
Results—Cats anesthetized with the low dose of propofol had consistent detrusor reflexes, compared with results for the other anesthetics. Mean ± SD threshold pressure, volume per unit of body weight, and compliance were 75.7 ± 16.3 cm H2O, 8.3 ± 3.2 mL/kg, and 0.5 ± 0.4 mL/cm H2O, respectively, for low-dose propofol. Anesthesia with either dose of propofol caused a significantly higher percentage change in heart rate during the cystometrogram, compared with results for anesthesia with isoflurane. Maximal urethral pressure in the area corresponding to skeletal muscle and the maximum urethral closure pressure were significantly higher for the low dose of propofol, compared with results for the high dose of propofol.
Conclusions and Clinical Relevance—The low-dose propofol regimen was the easiest to titrate and maintain and yielded diagnostic-quality detrusor reflexes in all 6 cats. Anesthetic depth should be titrated appropriately when performing urodynamic procedures.
Objective—To determine the effects of stress in cats with feline idiopathic cystitis (FIC) by evaluating bladder permeability, sympathetic nervous system function, and urine cortisol:creatinine (C:Cr) ratios during periods of stress and after environmental enrichment.
Animals—13 cats with FIC and 12 healthy cats.
Procedure—Cats subjected to an acute-onset moderate stressor for 8 days received IV injections of fluorescein. Serum fluorescein concentrations were determined and compared with those of controls to evaluate bladder permeability, and urine C:Cr ratios were compared to evaluate function of the hypothalamic-pituitary-adrenal (HPA) axis. Plasma catecholamine concentrations were analyzed in a subset of cats. After 8 days of moderate stress, cats were moved to an enriched environment, and tests were repeated after 21 days.
Results—Serum fluorescein concentrations were significantly higher in cats with FIC at all time points. In the cats in which plasma catecholamine concentrations were determined, concentrations of dihydroxyphenylalanine, norepinephrine, and dihyroxyphenylglycol were significantly higher in cats with FIC at all time points, whereas no differences in urine C:Cr ratio between groups were observed.
Conclusion and Clinical Relevance—Cats with FIC appeared to have altered bladder permeability, most notably during the period of initial stress. The increase in plasma dihydroxyphenylalanine concentration suggests that there may be stress-induced increase in the activity of tyrosine hydroxylase, which catalyzes the rate-limiting step in catecholamine synthesis. In contrast, no effects of stress on C:Cr ratios were observed, which suggests there was dissociation between the sympathetic nervous system and HPA-axis responses to stress.
Objective—To determine the mineral composition and anatomic location of urinary calculi and to investigate sex and reproductive status as predisposing factors for development of urolithiasis in potbellied pigs.
Design—Retrospective case series
Samples—Urinary calculi from 50 purebred and crossbred potbellied pigs.
Procedures—Laboratory records for urinary calculi of potbellied pigs submitted to the University of California-Davis Stone Laboratory from 1982 through 2012 were reviewed. Mineral composition of calculi was determined by polarized light microscopy, infrared spectroscopy, and, in some cases, x-ray diffractometry.
Results—Of the 48 urinary calculi analyzed by infrared spectroscopy, 21 (44%) were composed primarily of amorphous magnesium calcium phosphate; another 9 (19%) were primarily composed of calcium phosphate in the form of apatite. Of 50 urinary calculi, 22 (44%), 14 (28%), 10 (20%), 3 (6%), and 1 (2%) were removed from the urinary bladder only, urethra, both urinary bladder and urethra, urine, and renal pelvis, respectively. Sex of 6 potbellied pigs was not recorded. For 44 urinary calculi, 41 (93%) were from males (11 sexually intact males and 30 castrated) and 3 (7%) were from females (2 sexually intact females and 1 spayed). Among males, 73% (30/41) of submissions were from castrated males.
Conclusions and Clinical Relevance—In contrast to results from studies in commercial pigs, the most common composition of urinary calculi identified in purebred and crossbred potbellied pigs was amorphous magnesium calcium phosphate. Potential predisposing factors for urolithiasis in potbellied pigs may be similar to those for urolithiasis in commercial pigs. These include diet, urinary tract infections, and sex. Thus, prevention of urolithiasis should target these potential predisposing factors.
Objective—To evaluate trends in urolith composition and urolithiasis in dogs during the past 21 years.
Design—Retrospective case series.
Sample Population—25,499 uroliths and the dogs from which they were obtained.
Procedures—Database of the Gerald V. Ling Urinary Stone Analysis Laboratory was searched from January 1985 through December 2006. All uroliths from dogs and the accompanying submission forms were evaluated. Age, sex, breed, and urolith location were recorded.
Results—Minerals identified in uroliths included struvite, calcium oxalate (CaOx), urate, apatite, brushite, cystine, silica, potassium magnesium pyrophosphate, sulfa drug, xanthine, and newberyite. Although more struvite-containing uroliths were submitted during this period, a significant decrease in the proportion of struvite-containing uroliths submitted as a percentage of all uroliths submitted was detected. Also, a significant increase in the proportion of CaOx-containing uroliths submitted over time was detected. There was a significant nonlinear decrease in submission of urate-, silica-, and cystine-containing uroliths. The CaOx-, cystine-, and silica-containing uroliths were obtained significantly more often from male dogs; struvite- and urate-containing uroliths were obtained significantly more often from female dogs.
Conclusions and Clinical Relevance—An increase in the proportion of CaOx uroliths submitted over time was detected. Reasons for long-term changes in this trend were likely multifactorial and could have included alterations in diet formulations and water consumption and possibly the fact that people favor ownership of breeds more prone to developing CaOx-containing uroliths. The decrease in metabolic uroliths could have been related to better breeding practices and increased awareness of results of genetic studies.
Objective—To calculate the prevalence of urolithiasis in client-owned chelonians examined at a veterinary teaching hospital and to describe the clinical signs, diagnosis, and treatment of urolithiasis in chelonians.
Design—Retrospective case series.
Animals—40 client-owned turtles and tortoises with urolithiasis.
Procedures—The medical record database of a veterinary teaching hospital was searched from 1987 through 2012 for records of client-owned chelonians with urolithiasis. The prevalence of urolithiasis was calculated for client-owned chelonians examined at the hospital. Signalment and physical examination, hematologic, biochemical, urinalysis, diagnostic imaging, treatment, and necropsy results were described.
Results—The mean prevalence of urolithiasis in client-owned chelonians for the study period was 5.1 cases/100 client-owned chelonians examined. Thirty-one of the 40 chelonians were desert tortoises. Only 5 of 40 chelonians had physical examination abnormalities associated with the urogenital tract. Surgery was performed on 17 chelonians; 5 developed postoperative complications, and 4 of those died. Necropsy was performed on 18 chelonians, and urolithiasis contributed to the decision to euthanize or was the cause of death for 9. Uroliths from 13 chelonians were analyzed, and all were composed of 100% urate.
Conclusions and Clinical Relevance—Results indicated chelonians with urolithiasis have various clinical signs and physical examination findings that may or may not be associated with the urinary tract. Hematologic, biochemical, and urinalysis findings were nonspecific for diagnosis of urolithiasis. Many chelonians died or were euthanized as a consequence of urolithiasis, which suggested the disease should be identified early and appropriately treated.