Fluid therapy and medication to temporarily support the heart and blood vessels might be sufficient in many cases, but others require a transfusion with whole blood. | Photo: Anne M. Eberhardt/The Horse

Q.I recently had a horse that suffered major chest trauma, deep lacerations, major blood loss, etc. He went into hypovolemic shock due to the blood loss following the injury and a bad colic. He survived, but it was a very tough 24 hours. I thought I would look up some information about hypovolemic shock in horses online, but was surprised by the lack of information about shock related to blood loss, trauma, or emergency situations. What do I need to know?

—Erin Watt, via email

A.Shock can be defined as a critical state of hypoperfusion (poor blood delivery) of tissues. It means that some combination of circumstances is robbing the body of its ability to provide adequate blood flow to meet tissue needs. Think of it this way—in a complex multicellular organism like your horse, the only way to provide for the needs of each individual cell is to have a circulatory system that brings required nutrients to cells and removes waste products. This is called circulation, and without it the cells die