1) Excitable 2) Impetuous 
• (a.) Having hot blood; excitable; high-spirited; irritable; ardent; passionate.
Hot'-blood`ed adjective Having hot blood; excitable; high-spirited; irritable; ardent; passionate. 
Refers to horses having ancestors that trace to Thoroughbreds or Arabians Characteristics might include fineness of bone, thin skin, fine hair coat, absence of long fetlock hairs, and blood that makes it well-suited for speed and distance work
[adj] - prone to emotion
adjective prone to emotion; `hot-blooded Latin-Americans`
excitable; impetuous. · ardent, passionate, or virile. · adventuresome, exciting, or characterized by adventure and excitement. · (of livestock) of superior or pure breeding. · (of horses) being a Thoroughbred or having Arab blood.