What must a trainer do regarding the jockey before entering a horse in a race?

A trainer must secure the services of a jockey prior to entering a horse in a race because this is a critical step in the preparation process for racing. Having a jockey lined up in advance ensures that all participants are coordinated and that the horse has an experienced rider ready to compete on race day. This pre-arrangement is essential not only for the trainer's planning but also for maintaining the integrity and smooth operation of the racing event.

When a trainer enters a horse without securing a jockey first, it can lead to complications such as last-minute changes, which can affect the horse's performance and the overall betting landscape of the race. Proper planning and confirmation of a jockey's availability ahead of the entry help to avoid these issues, reinforcing the importance of this step in the racing protocol.