Ruel, a native of Soissons, was physician to François I. This book, commissioned by the king, was a Latin translation of a collection of excerpts from Greek veterinary writers on equine disease, compiled circa 900 CE: a Byzantine encyclopedia of horse medicine known as Hippiatrika. Nothing is known of many of the authors mentioned—Apsyrtus, Theomnestus, Eumelus, Hierocles, etc.— apart from these extracts. Digital facsimile from BnF Gallica at this link.

The collection was first published in Greek by Joannis Volderus of Basel, edited by Simon Grynaeus, in 1537.

The 5th and 6th books of Actuarius's De methodo medendi, concerning materia medica. Digital facsimile from the Internet Archive at this link.