Here's some fab information about the anatomy of your pony's circulatory system!

The heart

The heart is a muscle, used for pumping blood throughout your pony's body. In ponies, it is quite round and has four chambers: the left and right atria, and the left and right ventricles.

The average heart of an adult horse weighs 3.6kg — that's really heavy!

The blood and blood vessels

Blood consists of red blood cells (erythrocytes) and white blood cells (leukocytes), as well as plasma. Red blood cells are produced in the bone marrow and are responsible for carrying oxygen to all the cells. Rec blood cells also remove carbon dioxide.

White blood cells help the immune system by defending the body from pathogens.

Plasma suspends the red and white blood cells for easy transport around the body and is involved in clotting when an injury occurs.

The spleen

Damaged red blood cells are removed from the circulation by the spleen. It also holds extra blood cells which are released when they are needed.

Images courtesy of Gillian Higgins, horsesinsideout.com