ObjectivesThe objectives of this study were to identify the proportions of different types of uroliths, characterize the population of cats that present with urolithiasis and determine possible predisposing factors in a population of Mexican cats.MethodsThis study analyzed clinical specimens of feline urolithiasis submitted to our laboratory in the period from 2006 to 2017. The mineral composition of the uroliths was determined by qualitative and quantitative mineral analyses, performed by stereoscopic microscopy and infrared spectroscopy.ResultsIn the population studied, 54.3% of all uroliths were calcium oxalate, followed by 32.1% struvite and 7.4% purine (urate and xanthine) uroliths, with other types accounting for 6.2% of submissions. The male:female ratio was 1.2:1. Calcium oxalate submissions were predominantly from males and struvite submissions were predominantly from females. The age of the cats with stone submissions ranged from 6 months to 17 years. In cats with calcium oxalate uroliths, 52.3% were aged 7 years or older. Cats with struvite uroliths were younger, with 65.4% younger than 6 years of age. Almost 90% of all submitted uroliths were from domestic shorthair cats.Conclusions and relevanceThis is the first epidemiologic study of urolithiasis in cats in Mexico. Age and sex predispositions to common uroliths were identified, as males aged ≥7 years primarily presented with calcium oxalate uroliths and females aged <6 years primarily presented struvite uroliths. Cases of urolithiasis of genetic origin, including xanthinuria and cystinuria, were also detected, in addition to silicate uroliths.

Urolithiasis is a frequent and recurrent problem in dogs around the world. Several epidemiological studies based on mineral composition of uroliths have been carried out in different geographical areas. The objective of this study was to analyze epidemiological data of 195 dogs with urolithiasis from the metropolitan area of Guadalajara Jalisco, Mexico. To determine the chemical composition of uroliths, quantitative and qualitative analyses were performed by means of stereoscopic microscopy and infrared spectroscopy. The dogs` median age was six years and a male-female ratio of 1.4:1 was observed. The most affected pure breed dogs were schnauzer, poodle, Labrador retriever, Yorkshire terrier, and German shepherd. The frequency of uroliths of struvite, calcium oxalate, urates, mixes, and compounds, is similar to the one found in other studies performed in other populations. However, a much higher frequency of silicate-containing uroliths (16.92%) was observed, both in a pure form as well as in mineral mixtures. These results led us to suggest the need to develop further investigations to determine the origin of this high frequency.Figure 1. Different types of uroliths. Note the differences in shape, size, color, and number; however, none of these characteristics is specific to a particular mineral composition.

A higher frequency of canine silica urolithiasis is found in Mexico, unlike <1–8% in other countries. The causes and risk factors for this pathology are unknown. However, we consider the consumption of high amounts of silica from the solid diet or dissolved in water as the only hypothesis. This study aimed to identify the risk factors for silica urolithiasis in dogs from Mexico. A total of 1383 clinical cases of canine urolithiasis were included in this study; the uroliths were analyzed to determine their mineral composition by stereoscopic microscopy and infrared spectroscopy. Of these cases, 12.94% were considered pure silica uroliths; however, considering the mixed and compound uroliths, the frequency increased to 17.42%. Male dogs aged >6 years and large breeds, especially Labradors and Golden retrievers, were at significant risk for this disease. 98.88 % of the clinical cases studied were found in the central axis of the country, considering this finding as a possible geographical risk factor to be analyzed in another study.

Silica urolithiasis is infrequent in dogs, but in Mexico represents 12.9%. Our hypothesis is the consumption of high amounts of silicates in the diet, especially that dissolved in tap water. The objective of this study was to determine the concentrations of silica in the tap water in different geographical areas and their relationship with cases of silicate urolithiasis in dogs. From 179 cases of silicate urolithiasis, 98.9% were from dogs within a geographic area called the Trans-Mexican Volcanic Belt, which represents a cross shaft to the center of the country. Silica concentrations in tap water ranged between 3 and 76 mg/L, with a range of 27 to 76 mg/L, a mean of 49.9 ± 12 mg/L within the Trans-Mexican Volcanic Belt, and a concentration from 3 to 30 mg/L, with a mean of 16.4 ± 7 mg/L outside this area; these were significantly different ( p < 0.001 ). These findings demonstrate that there is a geographic risk factor for silicate urolithiasis in urolith-forming dogs, related to the consumption of tap water with a high concentration of silica. Further studies are necessary to identify this same pathophysiological association in other species.