Henry Clay McDowell bred Standardbred horses for harness racing, and Thomas became interested in the breeding and training of racehorses.

In the early 1900s, McDowell worked as a trainer for the Thoroughbred stable of William Kissam Vanderbilt in Kentucky.

McDowell is most notable as the breeder, owner, and trainer of the colt Alan-a-Dale, which won the 1902 Kentucky Derby.

[1][2] In 1925 Thomas McDowell acquired Buck Pond Farm in Versailles, Kentucky from the estate of Louis Marshall.

Joseph K. Nelson, a wealthy Chicago businessman and native of Woodford County, Kentucky, purchased the farm from McDowell's heirs in 1936.