Navicular Syndrome has been a problem for horses even longer than most of us realize; more than 3 million years, according to a researcher who has been studying fossil navicular bones from horses that lived in that age. 

Mary Thompson, a vertebrate paleontologist at the Idaho Museum of Natural History in Pocatello, Idaho, first became interested in this topic back in 1987 when her 8-year-old horse developed navicular syndrome. 

3 Million Years  Of Navicular

That got her to thinking about examining the navicular bones of Equus simplicidens, the first one-toed horses that weighed around 950 pounds and lived more than 3 million years ago. An examination that her team of researchers did with navicular bones from this species indicated 6 percent had bone lesions that could be directly linked to navicular syndrome.

Later, she examined the navicular bones from fossils of the heftier 1,150-pound Equus occidentalis that were  recovered from the La Brea tar pits in the Los Angeles, Calif., area. Among 119 navicular bones recovered from this species, 21 percent showed distinct signs of navicular disease.

In a presentation last fall at the annual meeting of the Society of Vertebrate Paleontology, Thompson pointed out that a horse’s weight likely plays a key role in the development of this disease. Her studies indicate that lighter weight equine species appear to have suffered less often from navicular syndrome than heavier weight horses.  

She also believes that the presence of a navicular syndrome condition in horses that freely roamed North America millions…