The shooting happened Tuesday afternoon in Domino Park, 1448 SW Eighth St. in Little Havana.
According to police, as the stray dog charged at the officer's horse, Sara
"The officer tried to avoid the horse from being attacked so he moved the horse out of harm’s way. The dog charged at the horse, bit her, forcing the officer to discharge his weapon striking the dog," police spokeswoman Kenia Reyes said in a statement.
Sara was taken to the Miami police stables for medical attention. She suffered injuries to a front and hind leg.
The dead dog was removed by Miami-Dade Animal Services, police said.
Police did not release the name of the officer who shot the dog.