Incidence of struvite urinary calculi in two ancestral lines of beagles.

In the last 17 years, 55 of 2,125 (2.6%) purebred beagles maintained in a closed colony had urolithiasis. Males comprised 72.7% of the affected animals. All the uroliths except one set in the kidneys were in the urinary bladder, the urethra, or both. All uroliths were nearly pure magnesium ammonium phosphate hexahydrate. Partially inbred beagles had a 10.7% incidence of urolithiasis, compared to a 2.0% incidence in an outbred line.