Police in Florida said they arrested a man who walked up behind a mounted officer and slapped his police horse on the hindquarters.
The officer wrote in the report of the incident that Izzy was startled and spun around.
The arrest report said the officer attempted to make contact with Waldner, who fled on foot.
"Officer Rine knew who I was talking about because he observed him run from me moments earlier," the arrest report states.
Waldner was booked on charges of injuring a police horse, resisting without violence and possession of cocaine. He was jailed in lieu of $1,250 bail.
Orlando police spokeswoman Michelle Guido said 13-year-old Izzy, a five-year veteran of the Orlando Police Department, did not require veterinary care after the incident.