Annette L. Ruby

Evaluation of trends in urolith composition and characteristics of dogs with urolithiasis: 25,499 cases (1985-2006)

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.

Dried solidified blood calculi in the urinary tract of cats.

We have noted an increased number of calculi submitted to the Gerald V. Ling Urinary Stone Analysis Laboratory, University of California, Davis, that do not contain crystalline material but appear to be composed of dried solidified blood (DSB). Canine and feline laboratory records from 1986-2003 were reviewed for samples composed of >99% DSB. No calculi from dogs were found, but specimens from 49 cats were composed of >99% DSB, of which almost half (n = 22) had been submitted after 2001. The DSB calculi had been removed surgically or by postmortem examination from all areas of the upper and lower urinary tract. All samples were well formed and could be divided in half with Rongeur forceps. Detailed case information was available for 12 cats. Urinalyses were available for 9 of the 12 cats, and the mean specific gravity was 1.017 (range, 1.009-1.032). Red blood cells were reported in the sediment of all cats, with most containing >100 RBC/hpf. Ureteral obstructions but no radio-opaque calculi were visible by radiography, including radiographic contrast studies. Reports of ultrasound examinations were available for 10 cats, and discrete calculi were not recorded. In addition to polarized light microscopy, infrared spectroscopy and electron probe microanalysis were performed on a subset (n = 6, DSB calculi; n = 3, control calculi) of samples. Significantly more carbon, nitrogen, and sulfur (P = .012, P = .02, and P = .012, respectively) were present in the elemental analysis of the DSB calculi than in the control calculi, suggesting that the DSB calculi are primarily formed from organic material. At this time, we are uncertain why these DSB calculi become solidified, and we recommend that samples be submitted both in formalin and preservative free to further investigate their etiology.

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.

Composition and characteristics of urinary calculi from guinea pigs

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.

Canine Uroliths: Analysis of Data Derived from 813 Specimens

This article contains an analysis of data compiled from 813 specimens of canine uroliths submitted to the Urinary Stone Analysis Laboratory at University of California School of Veterinary Medicine.

Methods of Analysis of Canine Uroliths

Accurate analysis of urinary calculi is essential for greater understanding of urinary stone disease and initiation of effective management and preventive measures. Quantitative and qualitative analysis of uroliths are discussed in this article.

Bacterial culture of uroliths. Techniques and interpretation of results.

This article discusses techniques of bacterial culture of uroliths, interpretation of results of culture, and antimicrobial therapy of bacteria associated with uroliths.

Mineral composition of urinary calculi from potbellied pigs with urolithiasis: 50 cases (1982-2012)

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.

Feline Urate Urolithiasis: A Retrospective Study of 159 Cases:

The objective of the study was to characterize the signalment, clinicopathologic data, and diagnostic imaging of cats with urate urolithiasis, as well as the salts of uric acid present in the uroliths. A retrospective analysis of feline urate uroliths submitted to the GV Ling Urinary Stone Analysis Laboratory between 2000 and 2008 was included. From these data, records were assimilated from referring veterinarians (143); furthermore, all recorded cases from within the William R Pritchard Veterinary Medical Teaching Hospital (16) were included. Median values for the complete blood count and chemistry panels available were within the reference intervals, when provided, with only a few outliers present. Of all cases evaluated, seven had a portosystemic shunt (PSS). Cats with urate uroliths and a PSS were younger than cats without a PSS (2 years vs 7 years). The pathogenesis of urate uroliths in cats is poorly understood. Most cats were not completely evaluated for a PSS, however, clinicopathologic parameters indicating hepatic dysfunction were seldom noted; more sensitive diagnostics such as serum bile acids were rarely performed to confirm or negate the presence of a shunt. Studies are warranted to evaluate pathogenesis of urate uroliths to tailor proper management and breeding strategies.

Diagnosis and treatment of urolithiasis in client-owned chelonians: 40 cases (1987–2012)

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.