RENAL CALCULI IN DOGS AND CATS - PREVALENCE, MINERAL TYPE, BREED, AGE, AND GENDER INTERRELATIONSHIPS (1981-1993)

Three hundred seventeen specimens of urinary calculi of renal origin f rom 214 female dogs and 103 male dogs, and 71 specimens of urinary cal culi of renal origin from 38 female cats and 33 male cats were submitt ed for mineral analysis between July 1, 1981, and December 31, 1993. A mong dogs, 45 breeds were affected with renal calculi. Thirty-three br eeds and a crossbred group were represented among females, but 8 breed s and the crossbred group accounted for 81% of the total. Among mate d ogs, 30 breeds and a crossbred group were represented, but 7 breeds an d the crossbred group accounted for 69% of the total. Among cats, 10 b reeds and a crossbred group were represented. Dogs and cats with renal calculi were older than these of 2 comparison population groups. More than one-half of the renal calculi in both dogs and cats were from th e Ist known episode of urolithiasis. The risk of formation of renal ca lculi was found to be higher for cats than for dogs, when compared to other stone-forming cats and dogs (approximately 4.95 per 100 stone-fo rming cats and 2.88 per 100 stone-forming dogs). Among dogs, breeds at highest risk of developing renal calculi were Miniature Schnauzers, S hih Tzus, Lhasa Apsos, Yorkshire Terriers, and female Pugs. Also at hi gh risk were male Dalmatians and male Basset Hounds. Among small dogs, females generally were at higher risk of developing renal calculi tha n were males. Regardless of size, terrier breed males generally were a t higher risk of developing renal calculi. Breeds of dogs at low risk for development of renal calculi included crossbreds, German Shepherd Dogs, Labrador Retrievers, Golden Retrievers, and female Dachshunds. W hen only 1 kidney was involved, the risk of left renal calculus was gr eatest for both dogs and cats, but bilateral renal involvement was rel atively common in both species (19% and 9%, respectively). Among dogs, specimens composed of 1 mineral substance (eg, struvite) occurred mor e often in males (58.3%) than in females (37.9%). Female dogs formed r enal calculi containing struvite or oxalate more often than did males; males formed calculi containing urate more often than did females. Ca lculi containing oxalate, apatite, or some combination of these minera ls predominated among cats; only 1 specimen from 38 female cats and on ly 4 specimens from 33 male cats contained neither oxalate nor apatite . Crossbred cats were significantly less likely to have renal calculi than were other breeds. A single renal calculus specimen was identifie d in several uncommon breeds including Tonkinese and Birman cats, and Affenpinscher, Clumber Spaniel, English Shepherd, and Field Spaniel do gs. No significant differences were observed between male and female d ogs or between male and female cars with regard to mineral type of the specimen rind the presence of urinary tract infection.