UROLITHIASIS IN DOGS I - MINERAL PREVALENCE AND INTERRELATIONS OF MINERAL-COMPOSITION, AGE, AND SEX

Objective-To compile and statistically analyze selected data from a la rge number of canine urinary calculi. Sample Population-11,000 specime ns: 5,781 from female dogs, 5,215 from male dogs, and 4 from dogs of u nrecorded sex. Procedure-Records were used to compile information from all canine calculi analyzed between July 1981 and January 1994. Inter relations of mineral composition, location of specimens within the uri nary tract, age and sex of affected dogs, and number of previous episo des of urolithiasis were determined. Results-Approximately 70% of the specimens were from a first episode of urolithiasis. Calculi were loca ted 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. Si gnificantly higher proportions of struvite, apatite, and urate were fo und in uroliths from females; oxalate, cystine, silica, and brushite w ere significantly more prevalent in males. Sixty-one percent of specim ens from males and 29% from females were composed of a single mineral substance. The most common mineral combination of 2 or more minerals i ncluded struvite and apatite. An additional 67 specimens from male dog s 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. Con clusions-Male and female dogs form urinary calculi composed of 1 or mo re of several distinct minerals. Prevalence of canine uroliths differs between ages and between the sexes. Many specimens contain complex la yering of minerals; most specimens were found in the urinary bladder. Clinical Relevance-Sex and age of dogs, mineral types of likely calcul i in males versus females, and their anatomic location are important c onsiderations for clinicians when evaluating risk in dogs with urolith iasis.