The Seanachie 02 - 'The horse that wouldn't gallop', by Gerry McCullough

Gerry reads the 2nd of her 'Old Seamus' series of 29 Irish stories, (originally published in 'Ireland's Own' - an Irish magazine produced in Wexford, Ireland).
Seamus happens to be out innocently after dark, when he hears something suspicious. His suspicions grow as he investigates further, but eventually the full facts force him to accept another conclusion.