Vascular hamartoma as the cause of hind limb lameness in a horse.

We report a 5-year-old gelding with a rare benign tumour of 2-month duration in the subcutis of the hind limb that presented with lameness. Physical examination revealed normal vital signs. Laboratory findings were within normal ranges. No bone abnormalities were detected on radiographic examination of the affected area. Bloody fluid was obtained by aspiration. Through an I-shape skin incision the tumour was excised en-block. Microscopic study showed a vascular hamartoma characterized by cavernous haemangiomatous tissue and proliferation of multiple vessels of variable diameter. This report highlights the importance of limb vascular hamartoma, as an infrequent lesion, in the differential diagnosis of lameness in the horse.