A seroma with accumulation of serum and lymph in the right hind limb where trauma has occurred. In this case it was also accompanied by injury to the muscles so that there was some degree of lameness. The diagnosis was made by ultrasound.
It is a benign but annoying complication for horses and manifests as a well-circumscribed swelling in the skin. The treatment was surgical drainage and excellent prognosis because it acted quickly.