Charles Carré, a French veterinarian and graduate of the Alfort Veterinary School in Paris, was dispatched to Iran in 1905 as the personal veterinarian to Mohammad Ali Mirza, the Crown Prince (later Mohammad Ali Shah Qajar). During his four-year residence in Iran (two years in Tabriz and two years in Tehran), he compiled the first comprehensive scientific report on equine diseases in Iran. This report, a copy of which has recently been discovered in the library of the Alfort Veterinary School, contains valuable information on the state of traditional veterinary medicine in Iran, contagious and non-contagious equine diseases, Iranian customs and practices concerning animal care, and the confrontation between traditional medicine and modern medicine during the Qajar period. This article introduces this report and its significance in the history of veterinary medicine in Iran, and demonstrates how this historical document can contribute to a better understanding of the background of veterinary medicine in Iran and animal diseases.