n.

one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse

any means of control

"he took up the reins of government"

For remote control of a reined animal by an operator
CREATIVITY REIGNS (Not Reined) in the Regular Classroom
Saddled: How a Spirited Horse Reined Me in and Set Me Free
Saddled: How a Spirited Horse Reined Me in and Set Me Free
Inflammatory arthritis can be reined in by CpG-induced DC–NK cell cross talk
THEY'RE OFF! Randy Punters' Racy Plans Reined in by Garda Prostitute Bust
Wu, H. J. et al. Inflammatory arthritis can be reined in by CpG-induced DC-NK cell cross talk. J. Exp. Med. 204, 1911-1922
Welfare concerns in the training and competition of the cutting, reining, and reined cow horse.
Fall meeting of the American Geophysical Union. Galloping glaciers of Greenland have reined themselves in
Reining in Angola's Yellow Fever Outbreak: Rosa Moreira Tells Andreia Azevedo Soares How Angola Reined in Its Worst Yellow Fever Epi...