Three-Dimensional Analysis of Round Window Membrane in the Chinchilla Model with Acute Otitis Media Induced with Streptococcus Pneumoniae 7F.

OBJECTIVE: The purpose of this study was to investigate the morphological changes of round window membrane (RWM) in chinchillas with Streptococcus pneumoniae (S. pneumoniae) serotype 7F induced acute otitis media (AOM) by two dimensional (2D) and three dimensional (3D) measurements. METHODS: Temporal bone specimens taken from 12 chinchillas were divided into two groups. The control group consisted of healthy animals that were injected with intrabullar saline. The subjects in the experimental group were induced with AOM by intrabullar injection of S. pneumoniae 7F. The 2D and 3D measurements of RWM were compared between the groups. RESULTS: Dramatic changes were noted in the RWM of the experimental group compared to the control group. The thickness [mean ± standard deviation (SD)] of the RWM was significantly (p<0.05) increased in the experimental group compared to the control group by 2D measurements taken at three different points of RWM. Moreover, 3D measurements revealed that the volume (mean ± SD) of RWM was significantly (p=0.009) increased in the experimental group. CONCLUSION: The results of our study, which indicated significant change in RWM in both 2D and 3D measurements, may shed light on the relationship between AOM and inner ear diseases. Based on our results, we recommend evaluating 3D analyses of RWM, which provide useful data, to better understand the changes in the membrane.

Cochleosaccular (Scheibe) dysplasia in dogs: A temporal bone study.

The objective of this study was to evaluate any otopathologic changes in temporal bone specimens from dogs with deafness related to cochleosaccular (Scheibe) dysplasia (CSD). We used the canine temporal bone collections of the Otopathology Laboratory at the University of Minnesota and of the Massachusetts Eye and Ear Infirmary at Harvard University in Boston. Our morphometric analysis included measuring the areas of the stria vascularis and the spiral ligament and counting the number of spiral ganglion cells. In addition, we noted the presence of the organ of Corti and cochlear hair cells, assessed the location of Reissner's membrane and the saccular membrane, and counted the number of both Type I and Type II vestibular hair cells in the macule of the saccule and vestibular ganglion cells. In the group of specimens from dogs with cochleosaccular dysplasia, we observed generalized degeneration in the cochlea and a significantly decreased number of Type I and Type II vestibular hair cells and vestibular ganglion cells. As hereditary deafness is presently untreatable with known therapeutic methods, dogs with cochleosaccular dysplasia should not be considered for breeding. Future therapeutic approaches, such as stem cell therapies, should be designed to target all the elements of the cochlea in addition to the saccule as it was found that both are affected in dogs with CSD.

L'objectif de la présente étude était d'évaluer tous changements otopathologiques dans des spécimens d'os temporal provenant de chiens avec surdité reliée à de la dysplasie cochléosacculaire (Scheibe) (DCS). Nous avons utilisé la collection d'os temporal canin du Otopathology Laboratory à l'Université du Minnesota et du Massachusetts Eye and Ear Infirmary de l'Université Harvard à Boston. Notre analyse morphométrique incluait de mesurer les régions de la stria vascularis et du ligament spiral et de compter le nombre de cellules du ganglion spiral. De plus, nous avons noté la présence de l'organe de Corti et des cellules ciliées cochléaires, évalué la localisation de la membrane de Reissner et de la membrane sacculaire, et compté le nombre de cellules ciliées vestibulaires de Type I et Type II dans la macule du saccule et les cellules vestibulaires ganglionnaire. Dans le groupe de spécimens provenant de chiens avec dysplasie cochléosacculaire, nous avons observé une dégénérescence généralisée de la cochlée et une diminution significative du nombre de cellules ciliées de Type I et Type II et ces cellules du ganglion vestibulaire. Étant donné que la surdité héréditaire est présentement non-traitable par des méthodes thérapeutiques connues, les chiens avec de la dysplasie cochléosacculaire ne devraient pas être utilisés pour la reproduction. Des approches thérapeutiques futures, telles que les thérapies avec des cellules souches, devraient être planifiées afin de cibler tous les éléments de cochlée en plus du saccule étant donné qu'il a été démontré que les deux sont affectés chez les chiens avec DCS.(Traduit par Docteur Serge Messier).

The Impact of Systemic and Local Administration of Ascorbic Acid on Traumatic Perforation of Tympanic Membrane and Myringosclerosis.

OBJECTIVE: In the present study, tympanic membranes (TM) harvested from myringotomized rats were analyzed histopathologically to compare the systemic and local effects of ascorbic acid on the development of myringosclerosis. MATERIALS AND METHODS: Forty male Wistar-Albino rats weighing between 350-400 g were included in this study. Under otomicroscopic examination, a standard 2-mm myringotomy incision was made on the posteroinferior quadrant of the TM of both ears. Rats were randomized into five groups as control, topical ascorbic acid 50 mg/kg, systemic ascorbic acid 50, 100, and 200 mg/kg groups, each group containing eight rats. On the 15th day of the study, the rats were decapitated, and bullas of the rats were extracted. Sections were stained with hematoxylin-eosin and examined through light microscopy. Inflammation, distribution width of plaques, edema, and neovascularization were observed on the lamina propria. Thickness of the TM was evaluated under the microscope and scored semiquantitatively. RESULTS: When intergroup comparisons of parameters related to total TM thickness were performed, differences between the control group and topical AA (ascorbic acid) or systemic treatment groups were found to be statistically significant (p<0.005). A statistically significant difference was detected among control, topical and systemic 200 mg/kg ascorbic acid groups for the edematous lamina propria (p=0.003 and p<0.05, respectively). CONCLUSION: For the total TM thickness, systemic and topical ascorbic acid use was effective when compared with the control group. It has been concluded that systemic use of higher doses of (200 mg/kg) ascorbic acid is beneficial in the resolution of the edematous lamina propria.

Efficacy of two commercially available, low-magnesium, urine-acidifying dry foods for the dissolution of struvite uroliths in cats.

OBJECTIVE: To compare the efficacy and safety of using 2 commercially available, low-magnesium, urine-acidifying dry foods to dissolve sterile struvite uroliths in cats. DESIGN: Prospective, multicenter, randomized clinical trial . SAMPLE: 37 cats with presumed struvite uroliths. PROCEDURES: Cats were randomly assigned to be fed 1 of 2 low-magnesium, urine-acidifying dry foods (food A or B). For each cat, physical examination, urinalysis, and abdominal radiography were performed weekly to assess treatment response. RESULTS: 32 cats had complete urolith dissolution. Mean ± SD times for a 50% reduction in urolith size (0.69 ± 0.1 weeks) and complete urolith dissolution (13.0 ± 2.6 days) were significantly shorter for cats fed food A, compared with those (1.75 ± 0.27 weeks and 27.0 ± 2.6 days, respectively) for cats fed food B. At study termination, mean ± SD urine pH (6.083 ± 0.105) for cats fed food A was lower than that (6.431 ± 0.109) for cats fed food B. In 5 cats, uroliths did not dissolve and were subsequently determined to be composed of 100% ammonium urate (n = 4) or 100% calcium oxalate (1). Adverse events associated with diet were not observed in any of the cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that dietary dissolution is safe and effective for eradication of sterile struvite uroliths in cats. Cats fed food A had faster urolith dissolution than did cats fed food B. Lack of a reduction in urolith size at 2 weeks after diet initiation was indicative of misdiagnosis or noncompliance.

Epidemiological evaluation of cystine urolithiasis in domestic ferrets (Mustela putorius furo): 70 cases (1992-2009).

OBJECTIVE: To determine the prevalence of cystine uroliths in domestic ferrets with urolithiasis and determine whether age, breed, sex, reproductive status, anatomic location, and season are risk factors associated with cystine urolith formation. DESIGN: Retrospective cross-sectional case-control study. SAMPLE: Records of 435 ferrets (Mustela putorius furo) with uroliths submitted for analyses between 1992 and 2009, of which 70 were cystine uroliths. PROCEDURES: Specific descriptive information was obtained about each ferret to determine whether specific risk factors were associated with the development of cystine uroliths. RESULTS: Cystine uroliths comprised 70 of the 435 (16%) uroliths. Cystine uroliths were more common in male (n = 54) than in female (16) ferrets. All cystine uroliths were retrieved from the lower portion of the urinary tract (bladder and urethra [n = 67]) or were voided (3); none of the uroliths were retrieved from the upper portion of the urinary tract (kidney and ureters). CONCLUSIONS AND CLINICAL RELEVANCE: Awareness of the prevalence of cystine uroliths along with knowledge of etiologic, demographic, and environmental risk and protective factors for urolithiasis may facilitate development of surveillance strategies that result in earlier detection of cystinuria. Genetic factors associated with this disease have not yet been reported in ferrets, but a familial pattern of inheritance determined to be a major underlying factor in cystine urolithiasis in dogs and humans suggests that this may be a factor in ferrets and that the parent stock of ferrets in the present study may have been inbred.

Effects of storage in formalin on composition of canine and feline uroliths.

OBJECTIVE: To determine whether storage in neutral-buffered 10% formalin in vitro has any effect on the composition of biogenic minerals of canine and feline uroliths. DESIGN: Prospective in vitro study. SAMPLE POPULATION: Canine and feline uroliths submitted to the Minnesota Urolith Center from 34 dogs and 27 cats. PROCEDURES: Submissions from each dog or cat consisted of multiple uroliths of a single mineral type. After retrieval from the urinary tract, none of the uroliths had been placed in a preservative before submission. Evaluated uroliths were exclusively composed of the following: only struvite (uroliths from 5 dogs and 5 cats), calcium oxalate (5 dogs and 5 cats), calcium phosphate apatite (5 dogs and 5 cats), cystine (5 dogs and 5 cats), ammonium urate (5 dogs and 5 cats), or silica (5 dogs). One urolith from each dog or cat was quantitatively analyzed by polarized light microscopy, infrared spectroscopy, or both. Another urolith from the same animal was immersed in 1 mL of neutral-buffered 10% formalin for 48 hours at room temperature (22.5°C). Uroliths exposed to formalin were then air-dried for 30 minutes, and the analysis was repeated. RESULTS: After exposure to formalin, a portion of every struvite urolith was transformed into newberyite. This was not observed with any other urolith mineral type. Quantitative mineral analysis of nonstruvite uroliths revealed no detectable change in mineral composition. However, 3 of 10 ammonium urate uroliths dissolved when placed in formalin. CONCLUSIONS AND CLINICAL RELEVANCE: To avoid misdiagnosis of mineral composition, uroliths should not be immersed in formalin prior to analysis.

Risk factors for urate uroliths in cats.

OBJECTIVE: To identify demographic factors associated with urate urolithiasis in cats and determine whether the rate of urolith submission to a laboratory had changed over time. DESIGN: Case series and case-control study. ANIMALS: Cases consisted of 5,072 cats with urate uroliths submitted to the Minnesota Urolith Center between January 1, 1981, and December 31, 2008. Controls consisted of 437,228 cats without urinary tract diseases identified in records of the Veterinary Medical Database during the same period. PROCEDURES: Information on cat breed, age, sex, reproductive status, and location of uroliths was used to identify risk factors. Changes in annual urolith submission rates were evaluated. RESULTS: Purebred cats had significantly higher odds of developing urate uroliths than did cats of mixed breeding (reference group). On the other hand, cats of the Abyssinian, American Shorthair, Himalayan, Manx, and Persian breeds had significantly lower odds of developing urate uroliths than did mixed breeds. Neutered cats were 12 times as likely to develop urate uroliths as were sexually intact cats. Cats in all age groups had significantly increased odds of developing urate uroliths, compared with cats < 1 year of age (reference group). Cats ≥ 4 but < 7 years of age had the highest odds of all groups and were 51 times as likely to develop urate uroliths as were cats < 1 year of age. Urolith submission rates did not change significantly with time. CONCLUSIONS AND CLINICAL RELEVANCE: Findings of this study suggested that the typical cat with urate uroliths was a purebred neutered cat, 4 to 7 years old, with uroliths in the bladder or urethra. This information may be helpful in predicting mineral composition of uroliths in vivo. However, no conclusions can be made regarding cause-and-effect relationships.

Epidemiology of struvite uroliths in ferrets: 272 cases (1981-2007).

OBJECTIVE: To confirm that the predominant mineral type in naturally occurring uroliths in ferrets is struvite; to determine whether age, breed, sex, reproductive status, geographic location, season, and anatomic location are risk factors associated with urolith formation in ferrets; to compare features of struvite uroliths in cats with those in ferrets; and to determine whether there is a logical evidence-based rationale for clinical trials of the safety and efficacy of diet-induced dissolution of struvite uroliths in ferrets. DESIGN: Retrospective case-control study. ANIMALS: 408 ferrets with uroliths (272 struvite uroliths) from the Minnesota Urolith Center, and 6,528 control ferrets from the Veterinary Medical Database. PROCEDURES: Historical information was obtained about each ferret. The association between proposed risk factors and outcome (struvite urolith formation) was assessed. RESULTS: Sterile struvite was the predominant mineral in uroliths in ferrets. Neutered male ferrets had a significantly increased risk of developing sterile struvite uroliths. A significant association was also found between increasing age and the detection of struvite uroliths. Struvite uroliths in ferrets were more likely to be retrieved from the lower urinary tract than from the upper urinary tract. CONCLUSIONS AND CLINICAL RELEVANCE: Knowledge of predominant mineral type in uroliths along with insight into etiologic, demographic, and environmental risk and protective factors for urolithiasis may facilitate development of surveillance strategies that result in earlier detection of uroliths in ferrets. Modification of risk factors, including dietary risk factors, may help to minimize urolith formation, dissolve existing uroliths, and minimize urolith recurrence.

Rate and frequency of recurrence of uroliths after an initial ammonium urate, calcium oxalate, or struvite urolith in cats.

OBJECTIVE: To determine frequency of and interval until recurrence after initial ammonium urate, calcium oxalate, and struvite uroliths in cats and whether breed, age, or sex was associated with increased risk for urolith recurrence. DESIGN: Case-control study. ANIMALS: 4,435 cats with recurrent uroliths. PROCEDURES: To identify recurrence of uroliths in cats for which uroliths were submitted for analysis at the Minnesota Urolith Center in 1998, the facility's database was searched for urolith resubmissions from the same cats between 1998 and 2003. Risk factors and differences in mean interval until recurrence were assessed. RESULTS: Of 221 cats with ammonium urate uroliths in 1998, 29 (13.1%) had a first and 9 (4.1%) had a second recurrence. Mean interval until recurrence was 22 and 43 months for the first and second recurrence, respectively. Of 2,393 cats with calcium oxalate uroliths in 1998, 169 (7.1%) had a first, 15 (0.6%) had a second, and 2 (0.1%) had a third recurrence. Mean interval until recurrence was 25, 38, and 48 months for the first, second, and third recurrence, respectively. Of 1,821 cats with struvite uroliths in 1998, 49 (2.7%) had a first and 3 (0.2%) had a second recurrence. Mean interval until recurrence was 29 months for first and 40 months for second recurrences. CONCLUSIONS AND CLINICAL RELEVANCE: These results provided insights into the frequency of urolith recurrence in cats. Because some uroliths associated with recurrent episodes probably were not submitted to our facility, our data likely represented an underestimation of the actual recurrence rate.

Efficacy and safety of laser lithotripsy in fragmentation of urocystoliths and urethroliths for removal in dogs.

OBJECTIVE: To characterize the efficacy and safety of laser lithotripsy in the fragmentation of urocystoliths and urethroliths for removal in dogs. DESIGN: Prospective case series. ANIMALS: 100 dogs with naturally occurring urocystoliths and urethroliths. PROCEDURES: Via cystoscopy, laser lithotripsy was performed to fragment uroliths. Basket retrieval and voiding urohydropropulsion were used to remove fragments. Postprocedural contrast cystography was performed to assess efficacy and safety. In 40 dogs, midstream urine samples were collected just prior to laser lithotripsy (day 0) and on days 1, 3, and 11 after laser lithotripsy to assess inflammation. RESULTS: Urolith removal was complete in 82% of dogs (52/66 with only urocystoliths, 17/17 with only urethroliths, and 13/17 with urocystoliths and urethroliths). Urolith removal was incomplete in 18 dogs; of these dogs, 9, 6, and 3 had urolith fragments >or= 3 mm, 1 to < 3 mm, and < 1 mm in diameter, respectively. Sex (female) was the most significant predictor for success. Median procedure time was 72 minutes. Two dogs developed urinary tract obstruction following laser lithotripsy. Hematuria was detected in 53% of dogs on day 0 and in 84%, 13%, and 3% of dogs on days 1, 3, and 11, respectively. Leukocyturia was detected in 13% of dogs on day 0 and in 47%, 0%, and 3% of dogs on days 1, 3, and 11, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that use of laser lithotripsy was a safe and effective alternative to surgical removal of urocystoliths and urethroliths in dogs.

Comparison of laser lithotripsy and cystotomy for the management of dogs with urolithiasis.

OBJECTIVE: To compare efficacy, required resources, and perioperative complications between laser lithotripsy and cystotomy for urolith (ie, urocystoliths and urethroliths) removal in dogs. DESIGN: Retrospective case-control study. ANIMALS: 66 dogs with urolithiasis treated by laser lithotripsy (case dogs) and 66 dogs with urolithiasis treated by cystotomy (control dogs). PROCEDURES: Medical records were reviewed. Complete urolith removal rate, resources (ie, duration of hospitalization, procedure time, anesthesia time, procedure cost, and anesthesia cost), and complications (ie, hypotension, hypothermia, incomplete urolith removal, and requirement of an ancillary procedure) were compared between cystotomy group dogs and lithotripsy group dogs. RESULTS: Duration of hospitalization was significantly shorter for lithotripsy group dogs, compared with cystotomy group dogs. Procedure time was significantly shorter for cystotomy group dogs, compared with lithotripsy group dogs. Cost of anesthesia was significantly less for cystotomy group dogs, compared with lithotripsy group dogs. No significant differences were found between cystotomy group dogs and lithotripsy group dogs with regard to urolith removal rate, procedure cost, anesthesia time, or any of the evaluated complications. CONCLUSIONS AND CLINICAL RELEVANCE: Laser lithotripsy is a minimally invasive procedure that has been shown to be safe and effective in the removal of urocystoliths and urethroliths in dogs. No significant differences were found in the required resources or complications associated with laser lithotripsy, compared with cystotomy, for removal of uroliths from the lower portions of the urinary tract of dogs. Laser lithotripsy is a suitable, minimally invasive alternative to surgical removal of urethroliths and urocystoliths in dogs.

Melamine and cyanuric acid-induced crystalluria, uroliths, and nephrotoxicity in dogs and cats.

This article discusses the 2007 recall of canned pet food because of concerns about adverse effects on kidney function of cats and dogs. The discovery of melamine and cyanuric acid in the foods is detailed. Case studies, including clinical, pathology, histology, and toxicology findings, are presented. An attempt is being made to identify the minerals in the uroliths and kidney tissues of affected animals.

Drug-induced urolithiasis.

The prevalence of uroliths that contain drugs, their metabolites, or toxic ingredients in dogs, cats, and other animals is unknown. The authors examine specific drugs and their use in the animal population. They discuss these drugs in terms of uroliths and urolith formation in a variety of animals, making recommendations on which drugs can be safely used based on evidence from the authors' own studies and the literature.

Quantitative analysis of 4468 uroliths retrieved from farm animals, exotic species, and wildlife submitted to the Minnesota Urolith Center: 1981 to 2007.

Knowledge of the mineral composition of uroliths in various species of animals can help veterinarians predict the mineral composition of stones in vivo. This information is important because dissolution of existing uroliths, or minimizing further growth of uroliths in situ, is dependent on knowledge of the mineral composition of uroliths. With this objective in mind, this report summarizes the results of quantitative mineral analysis of uroliths retrieved from 4468 animals sent to the Minnesota Urolith Center. It also encompasses the most extensive database about uroliths from animals other than domesticated dogs and cats found in the literature.

Changing paradigms in the treatment of uroliths by lithotripsy.

Surgery remains a common procedure for removal of uroliths from the lower urinary tract of dogs. Incorporation of intracorporeal laser lithotripsy and extracorporeal shock wave lithotripsy has provided impetus for a paradigm shift in the way veterinarians manage urinary stones, however. These minimally invasive techniques provide a successful alternative to surgical urolith extraction.

Paradigm changes in the role of nutrition for the management of canine and feline urolithiasis.

Results of experimental and clinical investigation have confirmed the importance of dietary modifications in medical protocols designed to promote dissolution and prevention of uroliths. The objectives of medical management of uroliths are to arrest further growth and to promote urolith dissolution by correcting or controlling underlying abnormalities. For therapy to be most effective, it must promote undersaturation of urine with lithogenic crystalloids by 1) increasing the urine solubility of crystalloids, 2) increasing the volume of urine in which crystalloids are dissolved or suspended, and 3) reducing the quantities of lithogenic crystalloids in urine. This article summarizes and applies evidence about nutritional management of urolithiasis derived from experimental and clinical studies of cats and dogs performed at the Minnesota Urolith Center.

[The investigation of short term efficiency of oxfendazole + oxyclozanide paste and tablet formulations against gastrointestinal nematodes in sheep]. / Koyunlarda Mide-Bagirsak Nematodlarina Karsi Oxfendazole + Oxyclozanide'nin Tablet ve Pasta Formülasyonlarinin Kisa Süreli Etkinliginin Arastirilmasi.

The aim of this study was to investigate the effectiveness of tablet and paste formulations of Oxfendazole and Oxyclozanide combinations against subclinical gastrointestinal nematode infections and to compare the advantages and/or disadvantages of their use. Seventy-five infected sheep were selected from an enterprise located in Kayseri in 2006. The sheep were divided into 3 equal groups as paste, tablet and control groups. Fecal samples were collected from each group before drug administration. While the paste and tablet groups were administered drugs orally, no drugs were given to the controls. Fecal samples were collected on the 7th, 14th, 21st, and 28th days after drug application and the EPG values were determined. The parasitological examination revealed that the most prevalent species was Ostertagia spp., followed by Nematodirus spp. and Trichostrongylus spp. While the mean EPG value of the control group increased up to a ratio of 7.8% at day 28, the mean EPG values of drug groups decreased to 0%. Although the unit dose of paste formulation is more expensive, it was found that it could be an alternative to tablet formulation and has some advantages such as being easier to give, effective utilizing, shorter application period, fewer complications and death risk, no application failure and requires fewer personnel.

Economical impact of tropical theileriosis in the Cappadocia region of Turkey.

This study was initiated to investigate the economical impact of vaccination against tropical theileriosis in cattle in Cappadocia in Turkey. A total of 554 vaccinated and non-vaccinated animals were monitored for Theileria annulata infection using microscopic examination serology by measuring the antibody response of the animals by the indirect immunofluorescence antibody test (IFAT). The prevalence of T. annulata infection, morbidity and mortality were significantly higher in unvaccinated than in vaccinated cattle, whereas the seropositivity was significantly lower in the unvaccinated group. Acute tropical theileriosis cases were diagnosed in 156 of 554 (27.61%) cattle, and 86 of 156 (56.21%) died from the disease. The total economic losses because of tropical theileriosis were estimated at US $598,133 for 2 years.

Evaluation of the association between sex and risk of forming urate uroliths in Dalmatians.

OBJECTIVE: To test the hypothesis that urate uroliths are uncommonly detected in female Dalmatians, compared with males. DESIGN: Case-control study. SAMPLE POPULATION: Medical records of dogs evaluated at veterinary teaching hospitals in North America from 1981 to 2002 and compiled by the Veterinary Medical Database, and records of dogs with uroliths submitted for quantitative analyses to the Minnesota Urolith Center from 1981 to 2002. PROCEDURES: Crude odds ratios (ORs) and 95% confidence intervals were calculated to assess whether sex (male vs female) was a risk factor for urate urolithiasis. RESULTS: In Dalmatians evaluated by veterinary teaching hospitals in North America, males were more likely (OR, 13.0) to form uroliths, compared with females. In Dalmatians that formed uroliths analyzed by the Minnesota Urolith Center, males were more likely (OR, 14.0) to form urate uroliths, compared with females. In all dogs (Dalmatian and non-Dalmatian) that formed uroliths analyzed by the Minnesota Urolith Center, males were also more likely (OR, 48.0) to form urate uroliths, compared with females. CONCLUSIONS AND CLINICAL RELEVANCE: When conducting studies and formulating generalities about urate urolithiasis in Dalmatians, it is important to consider sex-related differences in urolith occurrence. Long-term dietary or drug protocols designed to minimize formation of urate uroliths in male Dalmatians may not be warranted in female Dalmatians.

Trends in the frequency of calcium oxalate uroliths in the upper urinary tract of cats.

Medical records from cats diagnosed with uroliths at nine United States veterinary teaching hospitals from 1980 to 1999, and records of cats with uroliths submitted for analyses to the Minnesota Urolith Center from 1981 to 2000, were evaluated. A 10-fold increase in frequency of upper tract uroliths occurred in cats during the 20-year interval at the nine veterinary teaching hospitals. Calcium oxalate emerged as the predominant mineral type in upper tract uroliths, having increased more than 50-fold during the study period. These results emphasize the need for increased awareness of the occurrence of upper urinary tract uroliths in cats.