Handler (noun)

1. A person who is in charge of or responsible for a particular animal, especially a dog or horse.
2. A person who manages or deals with a particular situation or task.

Origin:

Handler (n.) 1650s, from handle (v.) + -er.

Examples:

1. The dog's handler trained him to do tricks.
2. He was the handler of the champion show dog.
3. She was the handler of the race horse.
4. He was a handler in the airport's baggage department.
5. She was the handler of the crisis management team.