An equine trocar and cannula is a veterinary surgical instrument used for emergency or planned procedures, most notably to decompress the gastrointestinal tract during severe gas colic. The device consists of a sharp, pointed trocar that fits inside a hollow cannula (sleeve). A veterinarian inserts the trocar and cannula to create a port into a body cavity, then removes the trocar, leaving the cannula in place for drainage or other instrumentation.