A haematoma is a collection of clotted blood beneath the skin or within a muscle.
The swellings usually occur immediately after the trauma that causes it. Depending on the affected body area, the hematomas can be of considerable size, especially at the flanks. A hematoma is usually spherical with a fuzzy edge. Upon touch it feels soft like a ball filled with liquid.
Following a blunt hit or an impact, vessels might be injured and blood can escape into the surrounding tissue.
Smaller hematomas disappear on their own when the body decomposes and absorbs the escaped blood. Larger hematomas occasionally cause pain and shall therefore be opened so that the accumulated blood can be discharged.
When the increased tissue growth becomes clearly larger, a veterinarian should be consulted. Otherwise, nothing is to be done.