One tall tale says that Kerry cattle grazing the seaweed along the coast of South Western Ireland mated with sea lions and produced the first Dexters. While the early history of the breed is a potpourri of fact and folklore, we do know Dexter cattle originated from that emerald land of Leprechauns. Dexters most likely evolved from the Celtic cattle that populated Ireland and date back to the Stone Age. Like Dexters, most of the Celtic cattle were predominately black although a dun cow was painted in the 1830’s by William Shiels to represent Irish Dexter/Kerry cattle. Professor David Low described Dexters in 1845 as being "various colors, as black, brown, and mixed black and white, or black and brown". Mr. Low’s publication in 1845 is also sometimes the account used for crediting a Mr. Dexter, an agent for Lord Howarden of Tipperary, for the name. Mr. Dexter is said to have selected from the best of the hardy mountain cattle of the region during the 1750’s in the development of the breed. The first herd book listing Dexter and Kerry cattle was issued in 1890.

While there are reports of Dexter cattle being introduced into England earlier, in 1882 Mr. Martin J. Sutton of Kidmore Grange, Oxfordshire purchased 10 Dexters from Mr. James Robertson of La Mancha, Dublin. The breed’s popularity grew and ten years later a Dexter/Kerry cattle society was formed. This small hardy breed that was utilized for milk and meat as the "poor man’s cow" in its native Ireland, ironically became the adoration of the gentry and thrived on English pastures.

Dexters were also in North America prior to the 1900’s. Between 1850 and 1900, Dexters were among some of the breeds of cattle imported to Hawaii. Around 1905, Dexters formed the herds for prominent individuals such as James J. Hill, Howard Gould, and August A. Busch. A herd book published in 1921 by the American Kerry and Dexter Club listed 63 registered Dexter bulls and 260 Dexter cows.

The claim that Dexters traveled on sailing ships to provide a source of milk and fresh meat seems believable given their docile temperament and broad distribution. The Irish Dexter has become the International Dexter with a growing worldwide interest. Pushed aside by larger more specialized breeds of cattle, Dexter cattle are listed as rare by the American Livestock Breeds Conservancy. In recent years their numbers have been rising as this naturally small breed has found favor among small landholders in North America, Britain, Australia, New Zealand, South Africa, Germany, and Holland. Whether it is a frozen tundra or tropical heat this ancient breed has probably been there. Today, this smallest of the European cattle breeds continues to sail into the hearts of everyone and continues to be hardy enough to establish itself everywhere.