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Also Known As

Blood blister


A hematoma is a "blood blister" caused by bleeding and oozing of serum under the skin, resulting in a swollen pocket of blood and tissue. The most common areas for hematomas are the hindquarters, chest, and along the ribs.


  • Soft lump on some part of the horse's body
  • A discolored purplish swelling
  • Nosebleed from one nostril in the case of ethmoid hematomas


Hematomas are caused by damage to soft tissue, resulting in bleeding and oozing of serum into a pocket or "balloon" under the skin. Hematomas are usually the result of being kicked by another horse, running into stationary objects, being pinched by tack, or falling down.


Since horses are active animals, the best prevention for hematomas is keeping the environment safe and practicing good horse management and training to prevent the kinds of situations where hematomas can result from injury.


Small hematomas will disappear spontaneously, as the blood and serum are absorbed by surrounding tissue. Large hematomas may need to be opened and drained with follow-up care to prevent infection.

Ethmoid hematomas, which are a pocket of blood that collects in the back of the nasal passages or in the sinuses, are treated by removing the mass and the tissue that is the source of the hematoma.

After diagnosis, small masses may be injected with formalin to cause them to dissolve. For large masses, removal of the tissue through the sinus bone flap may be necessary, with the horse under anesthesia. Laser surgery is also possible and produces good results. A veterinarian should be consulted as to the best diagnosis and procedure.

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EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.