Detrusor Myopathy in Beagle Dogs: A Rare but Notable Background Finding in Toxicologic Pathology
Detrusor myopathy, characterized by degeneration and regeneration of urinary bladder smooth muscle, remains an uncommon but significant background lesion in Beagle dogs. A review of recent historical control data (87 dogs across 12 studies) revealed no urinary smooth muscle findings. However, in 198 dogs from ongoing studies, detrusor myopathy was identified in 10 male animals (5.1%), with most cases linked to study sites employing catheterization for urine collection. Lesions were of minimal to moderate severity and lacked correlation with test article exposure, vascular changes, or consistent urinalysis findings. These observations reinforce the importance of recognizing catheterization-associated smooth muscle changes to avoid misattribution of this lesion as test article-related. Pathologists should consider detrusor myopathy a low-incidence, procedure-related background finding in the interpretation of urinary bladder histopathology.
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