Plenary Lecture: the Evolution of the Horse and Equine Dentistry - Any Connections?

The evolution of the modern horse (Equus caballus) has been studied more than that of any other animal and it is accepted that it began its evolution in the Americas (some dispute whether in North or South America) between 50 and 55 million years ago during the Eocene era. The horse evolved from a small rabbit- sized animal called Hyracotherium (also known as Eohippus or the dawn horse) whose skeletons are present in the National History Museum in London and in the Kentucky Horse Park Museum.Hyracotherium had 44 simple brachydont (short crowned) teeth similar to those of a human or dog, that were adequate for browsing on the soft leafy vegetation it consumed. Over the next few million years, possibly due to climatic and subsequent vegetation changes, Hyracotherium gradually adapted to survive on a totally different diet, i.e. grazing on less nutritious, cellulose- containing foodstuffs such as Tundra grasses. Despite cellulose being one of the most common foodstuffs on earth, mammals do not have any celluloytic enzymes and a simultaneous and necessary evolution in the horse was enlargement of its large intestine to allow fermentation of cellulose-containing foodstuffs by symbiotic bacteria, which allowed the horse to indirectly digest cellulose and so adapt to its changing environment. […]