Geographical cluster of renal hamartomas in wild urban white-tailed jackrabbits (Lepus townsendii).

Abstract

To understand diseases of wild urban jackrabbits (Lepus townsendii), we autopsied 130 individuals that died near roadways in Calgary, Alberta, Canada. Renal hamartomas were present in 8 of 130 hares (6.2%; 95% confidence interval: 3.2%-11.7%). Most were unilateral (7/8); one case had bilateral lesions. Hamartomas are benign, tumor-like lesions comprised of normal tissue elements in abnormal amounts and arrangements. Macroscopically, hamartomas were white, tan, or pink-red, well-circumscribed, singular or multilobular, expansile nodules in the cortex or corticomedullary junction. Histologically, renal hamartomas consisted of well-demarcated mature stromal tissue with fibrous tissue and occasionally, adipocyte differentiation. These results represent a unique temporal and geographical cluster of a renal anomaly in an urban wildlife population. Renal hamartomas were not identified in other large studies of diseases in free-ranging leporids including hares. Contributing factors to this cluster remain unknown.