Urinary Stone Analysis Research Articles

Evaluation of trends in urolith composition in cats: 5,230 cases (1985–2004)

To determine trends in urolith composition in cats. Retrospective case series. 5,230 uroliths. 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. 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. 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.

Urinary Stone Analysis of 1,000 Patients in Southern Taiwan

Urolithiasis is a common urologic disease. Stones may occur in the kidney, ureter, or urinary bladder. We collected 1,000 stone samples in the subtropical area of southern Taiwan. Stone components were analyzed by Fourier transform infrared spectroscopy. Mixed components of calcium oxalate and calcium phosphate were the most common form of stones (52.3%), followed by calcium oxalate (27.8%) and calcium phosphate (9.3%). Uric acid stones accounted for 7.6%. Magnesium ammonium phosphate stones accounted for 3.0%. Only one cystine stone was found. In the study of urinary stone formation mechanism and prevention of recurrent urolithiasis, knowing the stone composition is important.

Analysis of urinary calculi using an infrared microspectroscopic surface reflectance imaging technique

This investigation highlights the use of infrared microspectroscopy for the morphological analysis of urinary stones. The research presented here has utilized the reflectance mode of an infrared microscope for use in creating chemically specific maps of cross-sectioned renal calculi surfaces, precisely showing the placement of renal stone components in a calculus sample. The method has been applied to renal stones of both single and multiple components consisting primarily of hydroxyapatite, calcium oxalate monohydrate and calcium oxalate dihydrate. Factors discussed include the photometric accuracy of the spectra obtained, a comparison of the surface reflectance method with existing methods such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and attenuated total internal reflection (ATR) analysis, and the influence of specular reflectance between polished and unpolished sample spectra. Full spectral maps of cross-sectioned renal stones provided positive localization of components using qualitatively accurate spectra similar in appearance to DRIFTS spectra. Unlike ATR and DRIFTS spectra, surface reflectance spectra lack photometric accuracy and are therefore not quantifiable; at present, however, spectra are suitable for qualitative analysis. It was found that specular reflectance increases minimally with a highly polished stone cross-section surface, though qualitative data is not affected. Surface reflectance imaging of sections of renal stones is useful for determining the identity of stone components while simultaneously providing precise locations of mineral components within the stone using presently available instruments.

結石分析を施行した尿路結石症の臨床的検討

Stone analysis is an important examination for treatment and prevention of recurrence in urolithiasis. A twenty-six years clinical study of patient with urinary stone formers performed stone analysis was conducted. 1,108 stone formers (male 726, female 382) who performed stone analysis from 1977 to 2002 was conducted. Location of the stone, sex, age, treatment and stone analysis was examined in this study. Phase 1 is from 1977 to 1983 mainly performed open surgery, phase 2 is from 1984 to 1992 mainly performed endoscopic surgery, and phase 3 is from 1993 to 2002 mainly performed extracorporeal shock wave lithotripsy (SWL). Analytic numbers per year increased, especially phase 3. In the treatment of upper urinary tract (UUT) stone, open surgery, endoscopic surgery and SWL was carried out 78.4%, 72.8% and 71.4% of all cases in each phase. Many transurethral lithotripsy were performed for lower urinary tract (LUT) stone. The numbers of UUT and LUT stone were 1,007 and 101 cases. The frequency of LUT stone was higher than that found in a nationwide urolithiasis survey carried out in Japan in 1995. The male-female ratio of UUT stone was 2.35:1, 1.74:1 in phase 2 and 3. The frequency of female increased in phase 2 more than that in phase 3. The incidence of calcium oxalate stone was increased, calcium phosphate stone and infectious stone was significantly decreased in UUT and calcium containing stone in LUT was decreased. The average age for incidence of UUT stone rose in man step by step. The frequency in male was significantly higher than that in female under 50's, not significantly higher over 50's in calcium oxalate with calcium phosphate stone former (p = 0.009). In the present study, the clinical features were as follows : important urinary stone analysis, high frequency of LUT stone, high frequency in females, tendency to aging, high frequency of calcium containing stone in LUT, resolution of the difference in male and female over 50's in calcium oxalate with calcium phosphate stone former.

Establishing Composition and Structure of Intact Urinary Calculi by X-Ray Coherent Scatter for Clinical Laboratory Investigations

Current urinary stone analysis techniques are limited in their abilities to simultaneously characterize composition and structure. Laboratory techniques such as IRS and x-ray diffractometry require small powdered samples for analysis, rendering composition results dependent on the choice of sample and its preparation. We investigated the application of x-ray CS analysis to identify topographic urinary stone composition ex vivo. CS is essentially a transmission based x-ray diffractometry method that depends on molecular structure and, therefore, can distinguish different compounds. Diagnostic x-ray equipment facilitates the examination of structural arrangements of minerals in intact calculi. Tomographic images of intact calculi CS properties were acquired with a purposely built scanner. Composition is extracted from CS by fitting a library of common pure stone component CS signatures to those of the unknown sample in each image pixel. Two zones per stone were isolated (powdered) for IRS composition analysis for comparison with CS maps at these locations. Each stone was also independently analyzed for bulk composition by IRS analysis. CS composition maps revealed the spatial arrangement of minerals in intact calculi. IRS results showed good agreement with CS in the selected regions of interest. Bulk composition by IRS was noted to miss some important stone components, indicating that the choice of sample may skew composition results. CS from diagnostic x-rays can be used to identify structure and composition in mixed urinary calculi nondestructively. The tissue specific CS images presented support the development of CS analysis as a means of identifying stone composition characteristics in the laboratory.

Thirty-eight years of stone meetings in Europe

Of decisive importance for the many research groups all over Europe were the scientific symposia dealing with the theoretical foundations and clinical aspects of urinary stone disease. There were several sources from which today's European Urinary Stone meetings and the "Eurolithiasis Society" itself arose. It was a long way from Leeds in 1968 to Jena 1970, Bonn-Vienna in 1972 and to 11 European meetings from 1989 to 2005. Which developments in urinary stone disease research have been presented at our congresses during the past 40 years? The 1970s and 1980s are the years marked by efforts to measure the important lithogenic substances such as calcium, ionized calcium, uric acid, phosphate, oxalate with reliable methods. Hypercalciuria and specifically mild hyperoxaluria were the topics of numerous investigations in the 1970s, 1980s and 1990s. The calcium-loading test described by Pak has been discussed frequently since its application. It became apparent that oxalic acid is more important in urinary stone formation than hypercalciuria. Of importance were investigations done by Robertson and his colleagues on the influence of diet (in particular, an animal protein-rich diet) on urinary stone formation. Another emphasis of research was investigation of the crystallization process: supersaturation, crystal growth and aggregation are important steps in urinary stone formation. Of great importance in the formation of urinary stones are inhibitors (inhibitory activity): citrate, magnesium, pyrophosphate, macromolecules: GAGs, THP etc. and it became possible in the early 1970s to determine substances such as Tamm-Horsfall protein (THP) and GAGs. Much attention in the 1970s and 1980s was focused on urinary stone analysis (X-ray diffraction, infrared spectroscopy, polarization microscopy) and standardization of these methods. In the mid-1980s, a whole series of epidemiological studies were carried out, with data for the Federal Republic of Germany, East Germany, Czechoslovakia and Austria. The search for "stone-removing" medications, their description and clinical use was the subject of much clinical research and in vitro examinations. A definite advance occurred in the 1980s with the development of new instrumental technologies for the management of urinary stones such as shockwave ("Stosswelle") lithotripsy, percutaneous nephrolithotomy and ureterorenoscopy (" breakthrough innovations"). Since the 8th European Urolithiasis Symposium there have regularly been presentations pertaining to the topic of the molecular basis of inherited lithiasis. The last 10-15 years have shown an increasing turning toward the importance of cellular alterations and supersaturation and their relation to stone formation. In conclusion, I would like to note that it is of decisive importance for the research groups all over Europe to organize scientific symposia dealing with the theoretical foundations and clinical aspects of urinary stone disease under the protection of the European Urolithiasis Society.

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.

Laboratory coherent-scatter analysis of intact urinary stones with crystalline composition: a tomographic approach

Knowledge of urinary stone composition and structure provides important insights in guiding treatment and preventing recurrence. No current method can successfully provide information relating structure and composition of intact stones. We are developing a tomographic technique that uses measures of coherently scattered diagnostic x-rays to yield stone composition. Coherent-scatter (CS) properties depend on molecular structure and are, therefore, sensitive to material composition. Powdered, amorphous or polycrystalline materials with no significant orientation produce circularly symmetric CS patterns. However, in materials with preferred crystallite orientation, like urinary stones, bright spots in CS patterns are observed. This compromises a composition analysis based on comparing CS measurements from calculi to a library of CS signatures from powdered chemicals. We show that a computed tomographic reconstruction of CS measurements using filtered backprojection (CSCT) effectively eliminates bright spots and yields CS patterns equivalent to powdered materials. This allows for direct comparison with a powdered chemical reference library to establish composition. Validation is achieved through a tomographic CS analysis of an aluminium (Al) rod phantom. Much like calculi, CS patterns from a solid polycrystalline Al rod exhibit diffraction spots, absent in the ring-like Al powder CS pattern. We show that the reconstructed Al CS cross-section is equivalent to its powdered counterpart and results in clearly defined composition images. The potential of CSCT to identify stone composition is demonstrated through images of intact stones deemed chemically pure by infrared spectroscopy. Computed tomographic reconstruction of CS signals allowed the generation of composition maps, showing the distribution of stone components. These images provide strong evidence that current laboratory techniques risk missing critical stone components due to inadequate sampling. This is of particular importance since follow-up treatments are based on these composition analyses. CS analysis can distinguish common stone components and can provide topographic composition maps of intact stones. Such details offer invaluable clinical information regarding stone formation, treatment and follow-up, and thus support the development of CS analysis as a laboratory stone analysis technique.

Quality control in urinary stone analysis: results of 44 ring trials (1980–2001)

Urinary stone analysis is the most important diagnostic step after stone removal from the body. The methods employed for these analyses are based on diverse analytical principles. Chemical methods are used for detecting individual ions. Infrared spectroscopy is used for examining molecular structures, and X-ray diffraction for determination of the crystalline structure of a substance. Since 1980, a twice-yearly ring trials quality control survey has been on offer to examine the quality of urinary stone analyses. A summary of the results of 44 ring trials (1980-2001) has been compiled for individual pure substances and binary (two-component) mixtures. On average, 100 laboratories have participated in these ring trials. Initially, over 80% of the participants carried out their analyses using chemical methods. In 2001, this figure decreased to a mere 13%. In contrast, a progressive increase in the use of infrared spectroscopy was observed, up to 79% of all participants employed this method. X-Ray diffraction was only employed in a small number of specialised laboratories (5-9%). The chemical methods produced a very high proportion of errors (6.5-94%) with both the pure substances and binary mixtures, whereas high error rates for infrared spectroscopy and X-ray diffraction were confined to individual substances only. Due to the poor results in the ring trials, the majority of laboratories stopped using chemical analysis, which is now considered to be obsolete. Regarding mixtures, error rates of over 10% also occurred with infrared spectroscopy and X-ray diffraction. Ring trials are indispensable for the quality management of urinary stone analysis.

Infrared Spectroscopy in the Study of Renal Lithiasis

Infrared spectroscopic analysis of urinary stones is presented as a laboratory experiment for undergraduate students studying life sciences. Infrared spectroscopy, usually combined with the observation of macroscopic and microscopic features, is the preferred tool for unequivocal determination of renal stones composition. In this paper we represent and discuss the IR spectra of some of the most common types of urinary calculi occurring in humans and domestic animals.

A bleeding duodenal lipoma

Crystalluria is a marker of urine supersaturation with substances deriving from metabolic disorders, inherited diseases or drugs. The investigation of crystalluria must be done according to a protocol which includes the delivery to the laboratory of a proper urine sample, the use of a microscope equipped with polarized light, the accurate knowledge of urine pH, and a comprehensive examination of the crystals, which is based on their identification, quantification and size measurement. For unusual crystals, infrared spectroscopy may also be needed.If the formation of stones is always preceded by crystalluria, the reverse is not true. In addition to the crystalline composition, stone morphology provides valuable information on stone activity and, for some crystalline species, major information regarding the underlying pathology. Fourier transform infrared spectroscopy (FTIR) reliably identify specific forms of nephrolithiasis, as common-type stones made of calcium oxalate (CaOx) and/or calcium phosphate that is combined with morphology classification; using this method, stones may be classified into 6 types subdivided in 22 subtypes.The investigation of crystalluria is an inexpensive and valuable tool for the detection and the monitoring of inherited and acquired diseases associated with urinary stone formation or acute or chronic renal function impairment from intrarenal crystal precipitation.Selective FTIR identification of the composition of core (or the umbilication), middle part, and surface of every stone allows identification of the initiating lithogenic process (in the nucleus or in the Randall's plaque) and the factors which subsequently contributed to stone growth. In conclusion, the proposed morpho-constitutional method of urinary stone analysis, which moreover is rapid and low cost, provides clinically relevant orientations for targeted etiologic evaluation.

Infrared analysis of urinary stones: a trial of automated identification.

A Search algorithm included in the Opus software of Bruker (Germany) was evaluated for analysis of urinary stones. Three reference libraries containing respectively 85 (single components), 1,059 (binary mixtures) and 4,565 (ternary mixture) digitized spectra were created and used to identify unknown spectra (n=320), applying the automatic procedure. Identification of the major component was correct in 83% of cases but the percentage of identification significantly decreased for the second and the third components. In cases of identification of the two first components, quantitative assessment was correct within tolerance limits +/- 15%. The computer results are judged unsatisfactory with regard to pathology because computer-aided identification is not sufficiently sensitive and specific to differentiate species with similar spectral pattern, even for the identification of main component, and also to detect minor components. It can be of assistance to guide spectral analysis, but it cannot replace human identification.

Urolithiasis in dogs IV: Survey of interrelations among breed, mineral composition, and anatomic location of calculi, and presence of urinary tract infection

Abstract Objective To compile and analyze selected data from a large number of canine urinary calculus specimens that were subjected to quantitative, layer-by-layer mineral analysis. Sample Population 11,000 canine urinary calculus specimens: 5,781 from female dogs, 5,215 from male dogs, and 4 from dogs of unrecorded sex. Procedure Records of the Urinary Stone Analysis Laboratory, School of Veterinary Medicine, University of California were used to compile information regarding urinary calculus specimens from dogs. Records surveyed were of all canine calculi submitted for analysis between July 1981 and January 1994. Results analyzed included those of a mixed-breed group and 26 common breeds of stone-forming dogs. Interrelations of breed, sex, and age of the affected dogs, mineral composition of the specimens, and associated urinary tract infections were analyzed statistically. Results Proportions of culture-positive specimens were significantly correlated between the sexes (r = 0.494, P = 0.008). Staphylococcus intermedius was isolated most often from either sex, ranging from 36.1% (Basset Hounds) to 67.9% (Pekingese) of cultured specimens from females and 8.7% (Chihuahuas) to 71.4% (Scottish Terriers) of specimens from males. The second most frequently isolated bacterial species, Escherichia coli, ranged from 0% in males of 2 breeds and females of 4 breeds to 25% in Cairn Terrier males and 19.4% in Basset Hound females. Streptococcus spp were the third most frequently isolated bacterial species. Significant correlations between the sexes were found for percentages of calculi located in the urinary bladder (r = 0.490, P = 0.008), and for calculi voided in the urine (r = 0.503, P = 0.006). Conclusions Breed and sex differences in prevalence of urolithiasis- and mineral-associated bacterial infections are numerous. Staphylococcus intermedius was the most common isolate from specimens from all but 3 of 54 breed/sex groupings. For either sex, streptococcal infections were significantly related to proportions of calculi passed in the urine. (Am J Vet Res 1998;59:650–660)

Urolithiasis in dogs III: Prevalence of urinary tract infection and interrelations of infection, age, sex, and mineral composition

Abstract Objective To compile and statistically analyze selected data from a large number of canine urinary calculus specimens that were subjected to quantitative, layer-by-layer mineral analysis. Sample Population 11,000 canine urinary calculus specimens: 5,781 from female dogs, 5,215 from male dogs, and 4 from dogs of unrecorded sex. Procedure Records of the Urinary Stone Analysis Laboratory, School of Veterinary Medicine, University of California were used to compile information regarding all canine urinary calculus specimens submitted for analysis between July 1981 and January 1994. Interrelations of sex and age of the affected dogs, mineral composition of the specimens, and associated urinary tract infections were analyzed statistically. Results Urolithiasis was associated with growth of bacteria isolated from urine or calculi, or both, in 65% of females and nearly 44% of males. Staphylococcus intermedius was isolated most often from either sex (54% for females, 30% for males). In addition to staphylococci, 22 other bacterial species were isolated from specimens from females, and 17 other bacterial species and 1 species of yeast were isolated from males. A single bacterial species was isolated from 87.6% of cultures from females and from nearly 90% of cultures from males. Among females, nearly 98% of pure cultures of staphylococci were associated with calculi that contained struvite; this was true for 80% of pure cultures of staphylococci from males. Conclusions and Clinical Relevance There are wide sex differences in prevalence of urolithiasis- and specific mineral-associated bacterial infections. In several instances, bacterial infections were significantly related to urinary calculus location. These variables should be considered in any evaluation of canine patients that have uroliths. (Am J Vet Res 1998;59:643–649)

Use of Raman Spectroscopy for the Quantitative Analysis of Calcium Oxalate Hydrates: Application for the Analysis of Urinary Stones

The potential use of the Raman spectroscopy (RS) for the quantitative analysis of the mineral components of urinary stones consisting mainly of the mono- and dihydrate salts of calcium oxalate has been demonstrated. The quantitative analysis was based on the construction of calibration curves made of known mixtures of synthetically prepared pure calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD). The Raman spectra of well-mixed powdered samples of COM and COD were recorded, and the characteristic bands at 1462 and 1477 cm−1 for COM and COD, respectively, were used as the basis for the quantitative analysis. It was found that xM = ( IR – 0.134)/(0.8 IR + 1.52), where xM is the molar fraction of COM in the solid mixture and IR represents the intensity ratio of the Raman band at 1462 cm−1 to that of 1477 cm−1. The calibration curve was used for the analysis of a typical urinary stone surgically removed, and it was found that xM = 0.33. This finding was confirmed by infrared quantitative spectroscopic analysis. Quantitative analysis using the proposed Raman technique had a detection limit of approximately 0.6 mol % content in COM. The relative advantage of RS lies in its potential use as a nondestructive analytical technique for the mineral composition of urinary stones.

Recurrence rates and severity of urinary calculi.

During the last ten years, data of urinary calculi was received in 4094 cases on the criterion of "recurrence", whereby the answer was "yes" in 1446 cases. The overall "adjusted relative recurrence rate" (ARRR) is therefore 35.3%. The importance of an exact physical analysis of urinary stones, involving a differentiation of the various Ca oxalates and Ca phosphates, becomes clear looking at the high recurrence rates for the monomineralic stones of the Ca stone class like brushite and weddellite (ARRR = 66.7% and 50.0%, respectively) compared to apatite and whewellite (ARRR = 36.5% and 29.2%, respectively). Dramatic changes in the composition of the recurrent stone were observed only in 12.7% of all cases. The highest ARRR was found in infection stones with a large content of struvite (about 75%), whereas the total recurrence rate of the infection stone class was about 38%. An assessment of the "danger" of a urinary stone taking into account the criteria of "composition" and "prevalence to recur" is given.

Rapid computer-assisted infrared analysis of urinary calculi using photoacoustic detection.

The application of commercial spectrum-analysing software to quantitative analysis of urinary stones by Fourier transform infrared spectrophotometry is described. The infrared technique is straightforward in comparison with other stone analysis procedures of similar scope and affords significant time savings. The use of partial least squares regression in the analysis program enables better quantitation of stone components than has been hitherto possible using infrared methods. All the principal and many less common stone constituents can be detected and measured. Photoacoustic detection was employed, thus enabling non-destructive analysis with minimal sample preparation. A comparison is made between the infrared procedure and the hybrid thermogravimetric plus "wet" chemistry technique, which it has superseded for routine urinary stone analysis in the author's department.

Low-voltage SEM of urinary stones

Urinary stones are predominantly composed of calcium oxalate and calcium apatite while a minority of stones are formed from uric acid. The oxalate stones occur with greatest frequency, mainly in the form of the monohydrate (whellewite) with some dihydrate (wedellite) present. Despite many years of extensive research, the mechanisms for kidney stone nucleation and growth are still unknown. In particular the urine from recurrent stone formers, and the urine from those who do not form stones, does not show large differences in concentration of either calcium or oxalate ions. Recent work has emphasised the role of possible “inhibitors” or “promoters” in the growth of urinary stones though the quest for these substances remains elusive. Much effort has been devoted to the study of crystallization of calcium oxalates in an attempt to understand nucleation, aggregation and growth as a function of pH and the presence of possible promoters or inhibitors.Many analytical techniques have been applied to urinary stone analysis with X-ray diffraction, wet chemistry and infrared spectroscopy being the most successful for routine characterisation.

Urolithiasis in Dalmatians: 275 cases (1981-1990)

Summary From July 1, 1981 to December 31, 1990 the Urinary Stone Analysis Laboratory, School of Veterinary Medicine, University of California received 292 urinary calculi from 275 Dalmatians (14 females, 14 episodes; 261 males, 278 episodes). The mean age of dogs at the time of the first episode of calculus formation was 4.5 years for males and 5.5 years for females. Bacteria were isolated from 22 of 49 calculi (45%). The bacteria were gram-positive with 2 exceptions; coagulase-positive staphylococci accounted for 62.5% of the isolates. Polarized light microscopy was used to determine the mineral content of the calculi. One hundred ninety three calculi were 100% urate; 78 calculi contained ≥ 50% urate in 1 or more layers and were classified as mixed urate calculi; 7 calculi contained < 50% urate in all layers; and 14 calculi contained no urate. The secondary minerals most commonly encountered in mixed urate calculi were struvite (77%, 60 of 78 calculi), and oxalate (17%, 13 of 78 calculi). There were 65 struvite-containing calculi, 16 oxalate-containing calculi, 7 apatite-containing calculi, 5 silica-containing calculi, and 1 calculus specimen was composed of 100% cystine. The risk of forming urate-containing calculi was high in Dalmatians, whereas the risk of forming calculi containing other minerals was consistently lower in Dalmatians than in other breeds. X-ray diffraction and high pressure liquid chromatography were performed on all calculi from dogs known to have been given allopurinol (n = 19). One hundred percent of these calculi were found to contain xanthine or other compounds related to administration of allopurinol (eg, hypoxanthine, allopurinol, or oxypurinol).

Cystine‐containing urinary calculi in dogs: 102 cases (1981 to 1989)

One hundred and seven cystine-containing urinary calculi from 1 female and 101 male dogs were analyzed. Cystine-containing calculi accounted for 2% (107 of 5,375) of all canine urinary calculi submitted to the urinary stone analysis laboratory from July 1981 through December 1989. Male dogs that formed cystine calculi were compared with 3 other canine populations to determine whether certain breeds were apparently at increased or decreased risk for cystine calculus formation. In one or more of 3 population comparisons, significantly increased risk of cystine calculus formation was found in Mastiffs, Australian Cattle Dogs, English Bulldogs, Chihuahuas, Bullmastiffs, Newfoundlands, Dachshunds, Basenjis, Australian Shepherd Dogs, Scottish Deerhounds, Staffordshire Terriers, Miniature Pinschers, pitbull terriers, Welsh Corgis, Silky Terriers, and Bichon Frises. Significantly low risk of cystine calculus formation was found in German Shepherd Dogs, Poodles, Schnauzers, and mixed-breed dogs.