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

Abstract

Abstract 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 form 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. (Am J Vet Res 1998;59:624–629)