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  • Author or Editor: Annette L. Ruby x
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Abstract

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.

Design—Cross-sectional study.

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.

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in Journal of the American Veterinary Medical Association

Abstract

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.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To elucidate the ultrastructural details of calcium oxalate-containing urinary calculi from dogs.

Sample Population—38 specimens selected from a collection of 8,297 oxalate-containing urinary calculi from dogs: 22 specimens composed of calcium oxalate (calcium oxalate monohydrate [COM], calcium oxalate dihydrate [COD], or COM and COD) and 16 specimens composed of calcium oxalate with amorphous calcium phosphate.

Procedure—Analyses of specimens included use of plain, reflected, and polarized light microscopy, X-ray diffractometry, scanning electron microscopy (SEM) with backscattered electron (BSE) imagery, and electron microprobe analysis.

Results—Four texture types were observed in calcium oxalate calculi; 4 texture types of calcium oxalatecalcium phosphate-mixed calculi were recognized. Texture types were delineated through differences in calcium oxalate crystal sizes, which were affected by urine supersaturation and abundance of crystal nucleation sites. Segregation of calcium oxalate from calcium phosphate indicated they do not precipitate under the same conditions. Deposition of calcium phosphate between calcium oxalate crystals decreased the volume of pore spaces within calculi. Porosity was observed along boundaries between COM and COD. Minute pores increased the surface area of calculi exposed to urine, and this increase in liquid-solid interface promotes interaction of crystals with the surrounding urine.

Conclusions and Clinical Relevance—Calcium oxalate urolithiasis is of major concern, because it is often a recurrent disease among dogs, principally treated by surgical removal of calculi, with few effective dissolution strategies. Understanding the ultrastructure and mineralogic content of calcium oxalate and its association with amorphous calcium phosphate is a step toward the solution of this increasingly important medical problem. (Am J Vet Res 2001;62:237–247)

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in American Journal of Veterinary Research

Abstract

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.

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in Journal of the American Veterinary Medical Association

Abstract

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.

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in Journal of the American Veterinary Medical Association

Abstract

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.

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in Journal of the American Veterinary Medical Association