Born in Campbeltown, Scotland, the son of David McEachran and Jean Blackney, McEachran graduated from the Edinburgh Veterinary College in 1861 and received his license to practice from Royal College of Veterinary Surgeons. In 1862, he emigrated to Upper Canada setting in Woodstock. In 1863, he help set up, along with Andrew Smith, the Upper Canada Veterinary School (later the Ontario Veterinary College). In 1867, they published the first veterinary textbook in Canada for farmers, The Canadian horse and his diseases. In 1865, McEachran opened a private practice in Montreal where he moved the following year. In 1866, he helped to found the Montreal Veterinary College. In 1889, it would become the Faculty of Comparative Medicine and Veterinary Science of McGill University and McEachran became its first dean.