The latest attack, on neighbouring properties in Texas, follows the shooting two weeks ago of an eight-year-old Georgia horse, Misty, who was seriously injured when struck with hunting arrows.
The first Texas attack, in Tom Green County, was discovered on Sunday morning. A five-year-old female quarter horse named Baby was shot in each shoulder and near the tail. She was put down.
A neighbour about 300 metres away discovered her horse had been shot through the chest, the arrow passing right through. It is receiving treatment.
The Go San Angelo Standard-Times reports that police are pursuing leads, with a suspicious youth questioned by one of the horse owners on the road. He fled.
Evidence has been handed to local police, including a camouflage glove and a black arrow strap.