Compartment Syndrome is a rare cause of acute onset of severe unilateral forelimb lameness in horses. It is considered an emergency condition which occurs when pressure within a portion of a body compartment which contains muscles and nerves builds up to dangerous levels.

The increased pressure decreases blood flow to the affected tissues which prevents oxygen from getting to the nerve and muscle cells. Left untreated, this condition can result in permanent damage to the tissues and can cause a loss of function of the limb.

Compartment syndrome can occur due to trauma (collision with a fixed object, fall, or kick from another horse), thermal injuries, or wrapping a horse's legs too tightly. Compartment syndrome can occur in acute or chronic form. Acute form involves severe high pressure in the compartment following a single incident, and the chronic form is an exercised induced condition in which the pressure in the muscles increases to extreme levels during exercise.