Early-Onset Asymptomatic Polypoid Cystitis in Two Adolescent Male Beagle Dogs.

This brief communication describes a rare spontaneous background lesion in the lower urinary tract of two male laboratory beagles. Proliferative lesions comprising a constellation of histological features consistent with polypoid cystitis were observed in the bladder of two adolescent dogs from a routine preclinical toxicology study. Both animals were clinically asymptomatic and had only minor alterations in urinalysis parameters. While chronic polypoid cystitis is well-recognized in adult pet dogs, this is the first reported case in purpose-bred laboratory beagles. An awareness of this uncommon background finding is important for toxicological pathologists to distinguish it from potential test article-related findings.