trialler

English

Etymology

From trial +‎ -er.

Noun

trialler (plural triallers)

1. A horse or a dog used for trialling.
   • 2013, H. S. Lloyd, The Popular Cocker Spaniel‎:

     Ch. Doony Bluebell, Fairholme Trusty, Type, and Typist, are notable, while the blue roan, Fairholme Rally, has attained conspicuous success as a field trialler, and at stud was responsible for transmitting length of head, then much needed in the breed, and sired innumerable winners.