You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Hematomas are quite common and need to be treated properly

A hematoma is a collection of blood in a swelling. They can be  caused by a variety of injuries to blood vessels :

• Trauma - eg a direct blow, scratching, or shaking (eg of the ear)
• Damage to blood vessels by cancer
• Bleeding disorders eg blood clotting defects such as hemophilia, or vitamin K deficiency

Bleeding has to occur into a confined space, such as under the skin or in muscle,  to form a hematoma.

Common sites for hematoma formation are where there is a fractured bone,  in the ear flap (pinna) of cats and dogs, and horses often develop hematomas if they are kicked on their legs. In accessible parts of the body (such as the ear flap, or legs) surgery my be used to drain the hematoma and then close the space eg compress the skin flap against the underlying cartilage, to prevent it recurring. There are also alternative treatments which do not involve lancing the hematoma. At other sites (eg fractures) the heamatoma may not be drained, but blood loss into a hematoma can be quite significant and the animal may need a transfusion.

If a hematoma is left alone it is gradually reabsorbed into the body. However, it can cause problems at some sites. In the ear pinna for example a healing hematoma can cause the flap to stay thickened and become an uneven shape - called a "cauliflower ear". Sometimes this can close off the outer ear canal encouraging the development of ear infection.

Updated October 2013