Your horse has sustained trauma resulting in a generalized injury to an area. Rupture of small vessels in the injured tissues causes bruising, which is blood from tiny vessels that leaked into the space under the skin. Traumatic injury, inflammation of blood vessel walls (vasculitis), and clotting problems can all cause bruising.

What might you see when a horse has a bruise? You will see swelling. In a pink skinned horse, you might see a reddish or purplish bruise as you would under a pale-skinned human's skin. Once the vessels have stopped bleeding, inflammatory cells begin to clean up the red blood cells and digest their contents. The color changes (greenish and yellowish) seen over time represent the breakdown of the blood pigment hemoglobin. Since most horses have dark skin, we are not usually able to see this process taking place. We usually notice a contusion or bruise as simply swelling in an area.

Edema is different than bruising but is also often caused by trauma. Edema is fluid without actual blood cells, that has leaked from where it should be (inside vessels) to where it shouldn't be (within the adjacent tissue). Think of the "holes" in the vessels being smaller than in a bruise or hematoma, and not allowing the blood cells out, but allowing the fluid part of blood out. Think of edema as fluid trapped in tissues, as in a sponge. If you put a needle into a sponge, you would get nothing out.

A seroma is this same free fluid, without many blood cell- but rather than being stuck in the tissues like a sponge, it is trapped in a "low-pressure balloon". Your vet might decide to put a needle into a seroma and drain it.

A hematoma is a firm "ball" of free blood (often under some pressure initially) that has leaked out from a much larger vessel and is stuck in a particular location. This is different still.

A traumatic injury, depending on its nature, might mostly cause true bruising, or mostly edema. It might create a hematoma or a seroma. Your vet can differentiate all this and understands how to treat specific traumatic injuries.

When the cause of an injury is not known, trauma is a common fallback diagnosis for pain, swelling, and lameness. In horses, trauma often results from impacts from other horses or collisions with stationary objects. This impact causes swelling and inflammation, it breaks blood vessels and allows leaking of serum and blood into an area. The sum total of that might include bruising, edema, hematoma and seroma.

Importantly, in addition a traumatic may directly damages specific anatomic structures within the affected area. Trauma is considered as a cause for disease whenever appropriate.

DIAGNOSIS is by history, and veterinary examination/ assessment of an area, and exclusion of other causes.

TREATMENT- Bruises, hematomas, edema usually heal over time, or can be helped along. Rest is often also important to allow traumatic injury to heal. The real question is what important anatomic structures have also been injured. Will they need specific treatment?