General terms:
* High-spirited: This is a very common term used to describe a horse with a lot of energy and enthusiasm.
* Lively: This suggests a horse that is full of life and movement.
* Firey: This implies a horse with a hot temperament and a lot of passion.
* Excitable: This describes a horse that is easily stimulated and reacts strongly to its surroundings.
More specific terms:
* Hot-blooded: This term is often used to describe horses of certain breeds (like Arabians and Thoroughbreds) known for their spirited nature.
* Full of life: This emphasizes the horse's energy and zest for life.
* Full of beans: This is a colloquial term that implies the horse is very energetic and playful.
* High-strung: This suggests a horse that is easily nervous and sensitive.
Negative connotations:
* Strong-willed: This term implies that the horse is difficult to manage and doesn't always follow directions.
* Unruly: This describes a horse that is difficult to control and can be unpredictable.
* Nervous: This suggests a horse that is easily spooked and prone to reacting to things with fear.
Ultimately, the best term to use depends on the specific characteristics you want to convey about the horse.