This cross-sectional study describes the epidemiological data of feline urolithiasis in Thailand. Information on 923 feline uroliths submitted from Thailand to the Minnesota Urolith Center between January 2010 and December 2017 was evaluated. The frequency of urolith types, the relationships between urolith type and breeds and sex, were analyzed. Calcium oxalate was the most common urolith (49.5%) and was commonly found in male cats (OR = 1.81; 95%CI: 1.39, 2.36) with a mean age of 6.3±3.2 years. Struvite was the second most common urolith (38%), more frequently found in females (OR = 1.46; 95%CI: 1.11, 1.91) with a mean age of 5.1±3.1 years. Persians were significantly associated with the formation of CaOx urolith (OR = 1.65; 95%CI: 1.21, 2.21). Urate, cystine, calcium phosphate, and silica urolith were less common. Compound urolith was found in 7.6% of which 3 compound uroliths contained suture material as a nidus. During the study period, the proportion of CaOx urolith significantly increased from 35% in 2010 to 54% in 2017 (p < 0.01). The proportion of struvite urolith decreased from 54% in 2010 to 28% in 2017 (p < 0.01). The result of this study can be used for predicting the mineral composition of urolith and assist veterinarians to select diagnostic tests and to initiate therapy prior to urolith removal.

Purine uroliths (ammonium urate, sodium urate, calcium urate, uric acid, xanthine, 2,8-dihydroadenine, etc.) accounted for 4% (13,774 of 339,886) of all canine uroliths submitted to the Minnesota Urolith Center from 2012 to 2016 (Table 38-8). Purines accounted for 13.3% of all upper tract uroliths analyzed at the Minnesota Urolith Center from 2012 to 2016 (Table 38-9). Purines composed 23% of uroliths retrieved from dogs less than 12 months old. The mean age of dogs at the time of ammonium urate urolith retrieval was approximately four years (range one month to 17 years). The mean age of dogs at the time of sodium urate and calcium urate urolith retrieval was also approximately four years (range six months to 14 years). The mean age of dogs at the time of uric acid urolith retrieval was three years (range one month to 12 years). The mean age at the time of xanthine urolith retrieval was approximately five years (range one and one-half to nine years). Males were affected more often than females with ammonium urate (90 vs. 10%), sodium and calcium urate (99 vs. 1%), uric acid (88 vs. 12%) and xanthine (81 vs. 19%) uroliths. In our series, 66 different breeds were affected with ammonium urate uroliths including Dalmatians (61%), miniature schnauzers (7%), Yorkshire terriers (5%), Shih Tzus (4%) and English bulldogs (4%). Twelve different breeds had sodium and calcium urate uroliths; however, these uroliths were primarily encountered in Dalmatians (92%) and English bulldogs (4%). Six different breeds had uric acid uroliths; Dalmatians were affected most commonly (80%). Sixteen different breeds had xanthine uroliths, including Dalmatians (56%) and English bulldogs (35%). Ammonium urate (97%), sodium and calcium urate (96%), uric acid (100%) and xanthine “We should provide the type of medical care that we would desire if we were the patient rather than the doctor.” Carl A. Osborne 39

OBJECTIVETo identify demographic or signalment factors associated with calcium carbonate urolith formation in goats.DESIGNRetrospective case series and case-control study.ANIMALS354 goats with calcium carbonate uroliths (case animals) and 16,366 goats without urinary tract disease (control animals).PROCEDURESMedical records of the Minnesota Urolith Center were reviewed to identify case goats for which samples were submitted between January 1, 1984, and December 31, 2012. Control goats evaluated at US veterinary teaching hospitals in the same time period were identified by searching Veterinary Medical Database records. Age, breed, sex, reproductive status, geographic location, season, and anatomic location of collected uroliths were analyzed to identify risk or protective factors associated with calcium carbonate urolithiasis.RESULTSNigerian dwarf goats had higher odds of developing calcium carbonate uroliths than did Pygmy goats (reference group). Several breeds had lower odds of this finding, compared with Pygmy goats; odds were lowest for mixed, Anglo-Nubian, and Toggenburg breeds. Breeds of African origin (Pygmy, Nigerian Dwarf, and Boer) comprised 146 of 275 (53%) case goats with data available. Goats of African descent had a higher risk of developing calcium carbonate uroliths than did goats of non-African descent (reference group). Males and neutered goats had higher odds of calcium carbonate urolithiasis, compared with females and sexually intact goats, respectively. Age category, geographic location, and season were associated with detection of calcium carbonate uroliths.CONCLUSIONS AND CLINICAL RELEVANCEGoats with calcium carbonate uroliths were typically neutered males, > 1 year of age, and of African descent. This study identified factors associated with calcium carbonate urolithiasis in goats; however, these associations do not allow conclusions regarding cause-and-effect relationships.

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 degrees 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. (J Am Vet Med Assoc 2012;241:1613-1616)

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. (J Am Vet Med Assoc 2009;235:1450-1455)

This article is devoted to answering frequently asked questions from veterinarians, veterinary technicians, and pet owners about urolithiasis and the detection, treatment, and prevention of various types of uroliths from various locations in the urinary tract. It has been divided into the following topics: urolith analysis, urolith types, diagnosis, treatment and prevention, urolith recurrence, urinalysis, diet, water, and miscellaneous. The information is geared toward both professionals (eg, the chemical analysis of uroliths) and pet owners (eg, the practical considerations of diet). It includes photographs of various stones and a checklist of factors that suggest the probable mineral composition of canine uroliths.

Uroliths composed of calcium oxalate monohydrate and calcium oxalate dihydrate form as a result of the interaction of several different environmental and demographic risk factors, and several different metabolic disturbances.That is, not all calcium oxalate uroliths are “created in the same way.” Some of these factors are primary and some are compensatory. Identification of primary and secondary abnormalities associated with calcium oxalate urolithiasis is essential if therapy is to be consistently safe and effective. Of the biogenic uroliths that affect dogs, cats and people, those composed of calcium oxalate have been the most problematic. However, substantial progress has been made in the last 10 years. We predict that within the next 10 years, we will understand how to identify and safely modify the underlying mechanisms involved with calcium oxalate urolithiasis. That is, within the next decade we will have reached our goal of making the surgical removal of uroliths a treatment of historical interest. Calcium oxalate accounted for 38% of all canine uroliths submitted to the Minnesota Urolith Center from 1981 to 2007 (Table 38-8) and 41% (16,761 of 40,612) of all canine uroliths submitted in 2007 (Figure 40-1) (Osborne and Lulich, 2007). Calcium oxalate also accounted for 43% of all upper urinary tract uroliths analyzed at our Center from 1981 to 2006 (Table 38-9). From 2000 to 2006 calcium oxalate composed only 1% of uroliths retrieved from dogs less than 12 months old. The mean age of dogs at the time of calcium oxalate urolith retrieval was approximately 8.5 years (range = one to 25 years; median = 8.7 years). Males (74%) were affected more often than females (22%); the age of approximately 4% of affected dogs was not specified. A total of 214 different breeds were affected including miniature schnauzers (18%), mixed breeds (14%), Yorkshire terriers (9%), Bichon Frises (8%), Shih Tzus (7%), Lhasa apsos (5%), Pomeranians (4%), dachshunds (3%), Maltese (3%), Chapter 40

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.

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.

Urolithiasis is a general term referring to the causes and effects of stones anywhere in the urinary tract. Urolithiasis should not be viewed conceptually as a single disease with a single cause, but rather as a sequela of multiple interacting underlying abnormalities. Thus, the syndrome of urolithiasis may be defined as the occurrence of familial, congenital, or acquired pathophysiologic factors that, in combination, progressively increase the risk of precipitation of excretory metabolites in urine to form stones (ie, uroliths). The following epidemiologic discussion is based on quantitative analysis of 350,803 canine uroliths, 94,778 feline uroliths, and 6310 feline urethral plugs submitted to the Minnesota Urolith Center from 1981 to 2007.

OBJECTIVE To determine whether nephrolithiasis was associated with an increase in mortality rate or in the rate of disease progression in cats with naturally occurring stage 2 (mild) or 3 (moderate) chronic kidney disease. DESIGN Retrospective case-control study. ANIMALS 14 cats with stage 2 (mild) or 3 (moderate) chronic kidney disease (7 with nephroliths and 7 without). PROCEDURES All cats were evaluated every 3 months for up to 24 months. Possible associations between nephrolithiasis and clinicopathologic abnormalities, incidence of uremic crises, death secondary to renal causes, and death secondary to any cause were evaluated. RESULTS There were no clinically important differences in biochemical, hematologic, or urinalysis variables between cats with and without nephroliths at baseline or after 12 and 24 months of monitoring. No associations were detected between nephrolithiasis and rate of disease progression, incidence of uremic crises, or death. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that in cats with mild or moderate chronic kidney disease, nephrolithiasis was not associated with an increase in mortality rate or in the rate of disease progression. Findings support recommendations that cats with severe kidney disease and nephrolithiasis be managed without surgery.

Objective-To determine whether a renal diet modified in protein, phosphorus, sodium, and lipid content was superior to an adult maintenance diet in minimizing uremic episodes and mortality rate in cats with stage 2 or 3 chronic kidney disease (CKD). Design-Double-masked, randomized, controlled clinical trial. Animals-45 client-owned cats with spontaneous stage 2 or 3 CKD. Procedures-Cats were randomly assigned to an adult maintenance diet (n = 23 cats) or a renal diet (22) and evaluated trimonthly for up to 24 months. Efficacy of the renal diet, compared with the maintenance diet, in minimizing uremia, renal-related deaths, and all causes of death was evaluated. Results-Serum urea nitrogen concentrations were significantly lower and blood bicarbonate concentrations were significantly higher in the renal diet group at baseline and during the 12- and 24-month intervals. Significant differences were not detected in body weight; Hct; urine protein-to-creatinine ratio; and serum creatinine, potassium, calcium, and parathyroid hormone concentrations. A significantly greater percentage of cats fed the maintenance diet had uremic episodes (26%), compared with cats fed the renal diet (0%). A significant reduction in renal-related deaths but not all causes of death was detected in cats fed the renal diet. Conclusions and Clinical Relevance-The renal diet evaluated in this study was superior to an adult maintenance diet in minimizing uremic episodes and renalrelated deaths in cats with spontaneous stage 2 or 3 CKD.