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.

Silica-containing urinary calculi in dogs (1981-1993).

Silica-containing urinary calculi obtained from 773 dogs and submitted by veterinarians throughout the United States were analyzed by quantitative crystallographic analysis to determine mineral composition. Specimens were composed of either multiple mineral layers (535 specimens) or 1 mineral layer (238 specimens). Most multiple-layer calculi were composed of 80% or greater silica (300 of 535, 56%) or 20% to 79% silica (184 of 535, 34%) in any mineral layer. Most 1-layer calculi were composed of 100% silica (212 of 238, 89%). Most dogs forming silica-containing calculi were of male gender (679 of 773, 88%). Bacterial cultures of calculus or urine or both were performed on 49% (376 of 773) of the specimens, and bacterial growth was obtained from 37% (139 of 376) of samples cultured. The prevalence of calculus-associated urinary tract infection was 35% (113 of 321) in males and 47% (26 of 55) in females. The gender prevalence for infection with Staphylococcus species was 16% (51 of 321) in males and 33% (18 of 55) in females. The breed and gender of dogs that formed calculi (silica population) were compared with the hospital population (Veterinary Medical Teaching Hospital [VMTH] population) and with a population of calculus-forming dogs (Stonelab population) to determine risk factors for silica calculus formation. For all breeds compared, the ratio of males to females was higher in the silica population. The German Shepherd Dog and Old English Sheepdog were significantly overrepresented when the silica population was compared with either the VMTH population or the Stonelab population. We conclude that male German Shepherd Dogs and Old English Sheepdogs are at increased risk for formation of silica-containing urinary calculi.

Renal calculi in dogs and cats: prevalence, mineral type, breed, age, and gender interrelationships (1981-1993).

Three hundred seventeen specimens of urinary calculi of renal origin from 214 female dogs and 103 male dogs, and 71 specimens of urinary calculi of renal origin from 38 female cats and 33 male cats were submitted for mineral analysis between July 1, 1981, and December 31, 1993. Among dogs, 45 breeds were affected with renal calculi. Thirty-three breeds and a crossbred group were represented among females, but 8 breeds and the crossbred group accounted for 81% of the total. Among male dogs, 30 breeds and a crossbred group were represented, but 7 breeds and the crossbred group accounted for 69% of the total. Among cats, 10 breeds and a crossbred group were represented. Dogs and cats with renal calculi were older than those of 2 comparison population groups. More than one-half of the renal calculi in both dogs and cats were from the 1st known episode of urolithiasis. The risk of formation of renal calculi was found to be higher for cats than for dogs, when compared to other stone-forming cats and dogs (approximately 4.95 per 100 stone-forming cats and 2.88 per 100 stone-forming dogs). Among dogs, breeds at highest risk of developing renal calculi were Miniature Schnauzers, Shih Tzus, Lhasa Aposos, Yorkshire Terriers, and female Pugs. Also at high risk were male Dalmatians and male Basset Hounds. Among small dogs, females generally were at higher risk of developing renal calculi than were males. Regardless of size, terrier breed males generally were at higher risk of developing renal calculi. Breeds of dogs at low risk for development of renal calculi included crossbreds. German Shepherd Dogs, Labrador Retrievers, Golden Retrievers, and female Dachshunds. When only 1 kidney was involved, the risk of left renal calculus was greatest for both dogs and cats, but bilateral renal involvement was relatively common in both species (19% and 9%, respectively). Among dogs, specimens composed of 1 mineral substance (e.g., struvite) occurred more often in males (58.3%) than in females (37.9%). Female dogs formed renal calculi containing struvite or oxalate more often than did males; males formed calculi containing urate more often than did females. Calculi containing oxalate, apatite, or some combination of these minerals predominated among cats; only 1 specimen from 38 female cats and only 4 specimens from 33 male cats contained neither oxalate nor apatite. Crossbred cats were significantly less likely to have renal calculi than were other breeds. A single renal calculus specimen was identified in several uncommon breeds including Tonkinese and Birman cats, and Affenpinscher, Clumber Spaniel, English Shepherd, and Field Spaniel dogs. No significant differences were observed between male and female dogs or between male and female cats with regard to mineral type of the specimen and the presence of urinary tract infection.

Interrelations of organism prevalence, specimen collection method, and host age, sex, and breed among 8,354 canine urinary tract infections (1969-1995).

Selected information was compiled from canine urinalyses and urine cultures conducted between January 1969 and December 1995. Eight thousand three hundred fifty-four microbial isolates (bacteria and fungi) included 4,873 isolates from females and 3,481 from males. Ten bacterial genera accounted for 96.3% of the urinary isolates, including Escherichia coli (44.1%), Staphylococcus spp. (11.6%), Proteus spp. (9.3%), Klebsiella spp. (9.1%), Enterococcus spp. (8.0%), and Streptococcus spp. (5.4%) as the 6 most common isolates in both genders of dogs. Among these 6 genera, female dogs were generally predisposed over males, although males had more urinary tract infections (UTIs) caused by Klebsiella spp. Distributions of ages at UTI diagnosis tended to be similar between genders. Infection with a single microbial species was responsible for >72% of UTIs in both genders. Among females, 40 breeds and a mixed-breed group represented 90.2% of all positive urine cultures, 88.4% of the individual dogs with UTIs. and 88.2% of the microbial isolations. Among males, these same 41 breed groups represented 87.9% of all positive urine cultures, 87.6% of the individual dogs, and 88.2% of the microbial isolations.

Aerobic bacterial flora of the prepuce, urethra, and vagina of normal adult dogs.

Staphylococcus aureus and Mycoplasma spp were the most frequently isolated aerobic microorganisms in specimens obtained from the prepuce and the urethra of 20 normal, adult male dogs. Staphylococcus aureus and Streptococcus canis were the most frequently isolated bacteria in specimens collected from the vagina (in the area of the urethral orifice) of 20 normal intact bitches and 20 spayed bitches. A significant difference was not found in the observed frequency of occurrence of any of the microorganisms isolated from the intact vs the spayed bitches.

Relation of antibody-coated urine bacteria to the site(s) of infection in experimental dogs.

Antibody-coated bacteria tests, using fluorescein-conjugated rabbit anti-canine immunoglobulin (Ig)G and anti-IgA, were conducted on 77 specimens of bladder urine obtained by antepubic cystocentesis from 25 dogs with urinary tract infections. Urine specimens from 3 dogs infected with Staphylococcus aureus were tested a total of 27 times, specimens from 10 dogs infected with Escherichia coli were tested 25 times, urine from 6 dogs infected with Proteus mirabilis was sampled and tested 18 times, urine from 3 dogs with Klebsiella pneumoniae was sampled and tested 4 times, and specimens from 3 dogs infected with P rettgeri, Enterobacter cloacae, or Streptococcus faecalis were tested once each. Specimens of urine from the renal pelves of each dogs were obtained by percutaneous nephropyelocentesis at the same time as the specimens of bladder urine. The results of bacterial cultures of these specimens were compared with the results of the corresponding antibody-coated bacteria tests. False-positive results (ie, evidence of antibody coating of bladder urine bacteria but no bacterial growth from corresponding renal pelvis urine specimens) were obtained in 13 of 22 (59%) tests of dogs infected with S aureus, 12 of 13 (92%) tests in dogs infected with P mirabiis, 5 of 18(28%) tests in dogs infected with E coli, and 1 of 4 (25%) tests in dogs infected with K pneumoniae. False-negative results (ie, bacterial growth from renal pelvis urine specimens but no evidence of antibody coating of bacteria in the corresponding specimen of bladder urine) occurred in 5 of 7 (71%) specimens infected with E coli, in 4 of 5 (80%) specimens infected with P mirabilis, and in 5 of 5 (100%) specimens infected with S aureus. It was concluded that the antibody-coated bacteria test does not provide accurate information to support the diagnosis of pyelonephritis in the dog.

Urine concentrations of chloramphenicol, tetracycline, and sulfisoxazole after oral administration to healthy adult dogs.

Chloramphenicol, tetracycline, and sulfisoxazole were administered (orally) in separate trials to clinically healthy adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and an aliquot from each period was assayed for antimicrobial activity. Daily doses of the antimicrobics were as follows: chloramphenicol 99 mg/kg of body weight, tetracycline 55 mg/kg, and sulfisoxazole 66 mg/kg. Mean 8-hour urine concentrations (+/- 1SD) for chloramphenicol were 124 +/- 40 micrograms/ml; for tetracycline, 138 +/- 65 micrograms/ml; and for sulfisoxazole, 1,466 +/- 832 micrograms/ml. The mean 8-hour percentages of the doses of drug eliminated in active form in the urine were 6.3 +/- 2.6% for chloramphenicol, 11.2 +/- 2.0% for tetracycline, and 68.5 +/- 2.1% for sulfisoxazole.

Ultrastructure of selected struvite-containing urinary calculi from cats.

OBJECTIVE: To elucidate the ultrastructural details of struvite-containing urinary calculi from cats. DESIGN: Specimens studied were inclusive of the range of textures visible during preliminary analysis by use of a stereoscopic dissecting microscope. Textural types, which were used to infer crystal growth conditions, were differentiated with regard to crystal habit, crystal size, growth orientation, and primary porosity. SAMPLE POPULATION: Thirty specimens were selected from a collection of approximately 1,600 feline urinary calculi: 20 of these were composed entirely of struvite, and 10 consisted of struvite and calcium phosphate (apatite). PROCEDURE: Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron probe microanalysis. RESULTS: Four textural types were recognized among struvite calculi, whereas 2 textural types of struvite-apatite calculi were described. CONCLUSIONS: The presence of minute, well interconnected primary pores in struvite-containing urinary calculi from cats is an important feature, which may promote possible interaction of calculi with changes in urine composition. CLINICAL RELEVANCE: Primary porosity, which can facilitate interaction between the calculus and changing urine composition, may explain the efficacy of dietary or medicinal manipulations to promote the dissolution of struvite-containing uroliths from this species.

Ultrastructure of selected struvite-containing urinary calculi from dogs.

OBJECTIVE: To elucidate the ultrastructural details of struvite-containing urinary calculi from dogs. SAMPLE POPULATION: 38 specimens were selected from a collection of approximately 13,000 canine urinary calculi: 18 of these were composed entirely of struvite, and 20 consisted of struvite and calcium phosphate (apatite). PROCEDURE: Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron microprobe analysis. RESULTS: 4 textural types were recognized among struvite calculi, and 4 textural types of struvite-apatite calculi were described. Evidences of calculus dissolution were described from 4 calculi studied. CONCLUSIONS: The presence of small, well interconnected primary pores in struvite-containing urinary calculi from dogs appears to be a significant factor in determining the possible interaction of calculi with changes in the urine composition. The progress of dissolution from the calculus surface to the calculus interior appears to be largely affected by the primary porosity originally present between crystals forming the calculus framework. Apatite was observed to be more resistant to dissolution than struvite. CLINICAL RELEVANCE: The prevalence of fine concentric laminations having low porosity, and the common occurrence of apatite among struvite-containing urinary calculi from dogs may be 2 reasons why the efficacy of dietary and medicinal manipulations in dissolving urinary calculi is greater among cats than it is among dogs.

Urine concentrations of gentamicin, tobramycin, amikacin, and kanamycin after subcutaneous administration to healthy adult dogs.

Gentamicin, tobramycin, amikacin, and kanamycin were given subcutaneously in separate trials to healthy adult dogs of both sexes. Daily dosage levels were as follows: gentamicin, 6.6 mg/kg of body weight; tobramycin, 3 mg/kg; amikacin, 15 mg/kg; and kanamycin, 11 mg/kg. Gentamicin, tobramycin, and amikacin were given in divided doses of 8-hour intervals for 5 consecutive 8-hour periods, whereas kanamycin was given in divided doses at 12-hour intervals for 4 consecutive 12-hour periods. Mean 8-hour urine concentrations +/- 1 SD were gentamicin, 107 +/- 33 microgram/ml, tobramycin, 66 +/- 39 microgram/ml; and amikacin, 342 +/- 153 microgram/ml. Mean urine concentrations (+/- 1 SD) for kanamycin were 473 +/- 306 microgram/ml in urine collected between 0 and 6 hours after dosing and 63 +/- 47 microgram/ml in urine collected 6 to 12 hours after dosing.

Relationship of upper and lower urinary tract infection and bacterial invasion of uroepithelium to antibody-coated bacteria test results in female dogs.

Urinary tract infection was demonstrated in 12 female dogs via bacteriologic culture of a specimen of bladder urine collected by antepubic cystocentesis. Escherichia coli was isolated in pure culture from the urine of 9 dogs. Urine specimens from 2 dogs contained E coli and alpha-streptococci and from 1 dog contained Streptococcus zymogenes in pure culture. In 6 dogs, urinary tract infection was limited to the urinary bladder, whereas 6 dogs had unilateral or bilateral culture-positive renal pelvic urine as well (specimens collected by percutaneous nephropyelostomy). An antibody-coated bacteria (ACB) test was conducted on a portion of the bladder urine specimen from each dog, and the urinary tissues from these 12 dogs and from 6 healthy, noninfected female dogs were examined at necropsy. Tissues were given a subjective score based on the severity of the lesions seen microscopically. Histologic scores, bacterial cultural results, and ACB test results were examined for significance. A significant difference was found in the histologic scores between infected and noninfected dogs (P less than 0.025), but comparisons among histologic scores, cultural results, and ACB test results were not significant among infected dogs. The ACB test could neither be used to localize bacterial infection within the urinary tract nor could it be used to indicate the presence of bacterial invasion of the uroepithelium in dogs.

Staphylococci in canine urolithiasis: species identification, using a commercially available tray micromethod.

Fifty-one coagulase-positive staphylococcal isolates from canine urinary calculi or from the urine of dogs with documented urolithiasis, and 17 coagulase-positive staphylococcal isolates from human beings and cattle were identified by a commercially available tray micromethod, as well as by conventional methods. Canine isolates had previously been classified as Staphylococcus aureus on the basis of a positive tube coagulase test. After 5 hours' incubation, the tray method identified all 51 canine urolithiasis isolates as S intermedius, rather than S aureus. All human and bovine isolates were identified as S aureus. Conventional methods supported these findings.

Chronic urinary tract infection in dogs: induction by inoculation with bacteria via percutaneous nephropyelostomy.

Dogs were inoculated via percutaneous nephropyelostomy with bacteria isolated from canine patients with urinary tract infections (4 dogs were inoculated with Escherichia coli, 2 were inoculated with Proteus mirabilis, and 1 was inoculated with coagulase-positive staphylococci). At approximately monthly intervals after bacterial inoculation, bladder urine specimens were collected via antepubic cystocentesis, and renal pelvic urine specimens were collected via percutaneous nephropyelocentesis. Dogs were euthanatized between 89 and 294 days after bacterial inoculation. Extensive microscopic examination was conducted on the urinary tract of each dog. The dogs did not develop any of the common clinical signs of urinary tract infections (ie, increased frequency of urination, fever, craniodorsal abdominal [renal] pain, or malaise). Inflammation in the lower urinary tract of the dogs was more severe than that in the kidneys. Although pyelitis was present, extension into the outer medulla and renal cortex seemed to be confined to nephropyelostomy tracts. The most severe bladder lesion was found in the dog that developed cystic calculi after inoculation with coagulase-positive staphylococci.

Urolithiasis in dogs V: regional comparisons of breed, age, sex, anatomic location, and mineral type of calculus.

OBJECTIVE: To determine extent and nature of regional differences in distribution of canine urinary calculi. SAMPLE POPULATION: 13,552 calculus specimens: 7,056 (52.1%) from females, 6,492 (47.9%) from males, and 4 from dogs of unrecorded sex. Procedure Records were used to compile information from all specimens submitted between July 1981 and December 1995. Results from mixed-breed and various breeds of stone-forming dogs were analyzed. Interrelations of breed, sex, and age of dogs, and anatomic location and mineral composition of specimens were analyzed and compared for 6 US geographic regions. RESULTS: Struvite-, apatite-, and urate-containing calculi were reported significantly most often from female dogs of the Mountain/Pacific region. Oxalate-, silica-, and brushite-containing calculi were reported significantly most often from male dogs in the New England/mid-Atlantic (NEMA) region. Cystine-containing calculi were reported most frequently from the NEMA and South Central (SC) regions. Dogs from the NEMA region were oldest in average age at diagnosis. Significant regional differences in distribution were found for several breeds. Sex distribution of renal calculi in 11 breeds of dogs (Lhasa Apso, Yorkshire Terrier, Shih Tzu, Basset Hound, Pug, Mastiff, Bichon Frise, Doberman Pinscher, Dalmatian, English Bulldog, and Pekingese) reported to be at high risk of renal lithiasis differed among the 6 geographic regions. Renal and ureteral calculi were reported significantly most often from dogs in the South Atlantic region, and bladder and urethral calculi were reported most often from dogs in the SC region. CONCLUSIONS: Wide regional differences exist in distribution of stone-forming dogs by sex, average age at diagnosis, breed, and minerals contained within and anatomic location of calculi.

Ultrastructure and mineral composition of urinary calculi from horses.

Urinary calculi from 17 horses with urolithiasis were examined to study their mineral content and ultrastructure. Among the analytic methods used were X-ray diffractometry, scanning electron microscopy, and electron microprobe analysis. The calculi initially were observed by use of a stereoscopic dissecting microscope and generally were found to have nodular surfaces surrounding a banded or granular-to-chalky interior. Observation by scanning electron microscopy revealed an intricate pattern of irregularly concentric, fine bands and spherules. These had a round, finely banded, globular texture formed by precipitation of ultrafine-grained radiating crystals. The original pore spaces (ie, between spherules, between bands and spherules, or between crystal generations) could be observed as primary porosity. Precipitation and dissolution of these urinary calculi were observed to be spontaneous processes, which can occur simultaneously within an individual calculus. Another prominent feature of the ultrastructure was secondary porosity (spontaneous dissolution) which, in its incipient stages, appeared to be site-selective (ie, some bands appeared to be more susceptible to development of pinpoint porosity). Textures indicative of dissolution were observed not only on the calculus surface, but within the calculus interior as well. Areas that had more advanced stages of dissolution, resulting in increased secondary porosity, also were observed. All 17 samples of the study were found to be composed of calcium carbonate in the form of the mineral calcite, although minor quantities of 2 other polymorphs of calcium carbonate, minerals vaterite and aragonite, also were encountered. Vaterite was observed in 5 of the samples, whereas aragonite was found in 1 sample. Strontium and sulfur were observed as trace elements in 3 of the calculi, whereas magnesium was present in all calculi. Magnesium was observed to substitute for calcium within the calcite crystal lattice in larger quantities than those of strontium or sulfur. Magnesium K alpha X-ray dot maps generated by use of an electron microprobe analyzer indicated that the distribution pattern of magnesium appeared to closely follow layer-by-layer growth of the calculus. Magnesium distribution also appeared to be related to porosity development. In samples where preferential dissolution was observed, the more porous areas had higher magnesium content. Quantitative chemical analyses, using the electron microprobe analyzer, confirmed these observations. Association of the magnesium distribution pattern to the primary growth texture of the calculus indicated that magnesium content of the calculus varied during the formation process. This also indicated that changes in urine chemical analytes may be reflected in composition of the calculi formed.(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrastructure of selected calcium oxalate-containing urinary calculi from dogs.

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 oxalate-calcium 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.

Urolithiasis in dogs. I: Mineral prevalence and interrelations of mineral composition, age, and sex.

OBJECTIVE: To compile and statistically analyze selected data from a large number of canine urinary calculi. SAMPLE POPULATION: 11,000 specimens: 5,781 from female dogs, 5,215 from male dogs, and 4 from dogs of unrecorded sex. PROCEDURE: Records were used to compile information from all canine calculi analyzed between July 1981 and January 1994. Interrelations of mineral composition, location of specimens within the urinary tract, age and sex of affected dogs, and number of previous episodes of urolithiasis were determined. RESULTS: Approximately 70% of the specimens were from a first episode of urolithiasis. Calculi were located in the urinary bladder of 93.1% of females and 79.0% of males, and in the upper urinary tract of 4% of females and 2% of males. Calculi were found in multiple sites in 23.1% of males and 5.2% of females. Significantly higher proportions of struvite, apatite, and urate were found in uroliths from females; oxalate, cystine, silica, and brushite were significantly more prevalent in males. Sixty-one percent of specimens from males and 29% from females were composed of a single mineral substance. The most common mineral combination of 2 or more minerals included struvite and apatite. An additional 67 specimens from male dogs and 49 from female dogs contained other mineral combinations. In 48% of specimens from males and nearly 62% of specimens from females, the minerals formed several distinct layers of differing composition. CONCLUSIONS: Male and female dogs from urinary calculi composed of 1 or more of several distinct minerals. Prevalence of canine uroliths differs between ages and between the sexes. Many specimens contain complex layering of minerals; most specimens were found in the urinary bladder. CLINICAL RELEVANCE: Sex and age of dogs, mineral types of likely calculi in males versus females, and their anatomic location are important considerations for clinicians when evaluating risk in dogs with urolithiasis.

Urolithiasis in dogs. II: Breed prevalence, and interrelations of breed, sex, age, and mineral composition.

OBJECTIVE: To analyze selected breed-related data for canine urinary calculi. SAMPLE POPULATION: 11,000 specimens: 5,781 from female dogs, 5,215 from males, and 4 from dogs of unrecorded sex. PROCEDURE: Information was compiled for all canine urinary calculi submitted between July 1981 and January 1994. Results for a mixed-breed group and 26 of the most common breeds of stone-forming dogs were analyzed. Interrelations of breed, sex, and age of affected dogs and mineral composition of the specimens were determined. RESULTS: Prevalence of 5 specific mineral types was significantly correlated between the sexes of 27 common breed groups: struvite, calcium phosphate (apatite), calcium oxalate, brushite, and urate. Struvite-containing calculi were seen in high proportions in both sexes of 7 breeds, and in low proportions in both sexes of 7 other breeds. Male and female Lhasa Apsos, Cairn Terriers, and 5 other breeds had high proportions of oxalate-containing calculi; values in males were substantially higher. Low numbers of oxalate-containing calculi were seen in both sexes of 7 breeds; Dalmatians had the lowest numbers. Males and females of 6 breeds had high numbers of urate-containing calculi, Dalmatians and English Bulldogs had the highest numbers. Low amounts of urate were found in calculi from males and females of 6 breeds, Samoyeds had the lowest numbers. Highest proportions of cystine-containing calculi were seen in male Dachshunds, English Bulldogs, and Chihuahuas. Males of 8 breeds had no specimens that contained cystine; only 2 such specimens were obtained from females. CONCLUSIONS: Prevalence of uroliths differs among breed, age, and sex of affected dogs. CLINICAL RELEVANCE: Breed, sex, and age of dogs; mineral types of calculi in males versus females; and their anatomic location within the tract are important considerations for clinicians when evaluating risk in dogs with urolithiasis and in identifying areas that need further in-depth applied or clinical investigation, or both.

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

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.

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

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.