Five horses have been slashed with a blade in the Garstang area of Lancashire, England.
Lancashire police have urged horse owners to be vigilant following the attacks.
The first incident was in Winmarleigh, where a mare suffered two cuts across her legs.
Shortly after, four more mares in nearby Over Wyre were found with cuts in the buttock area.
Police urged other owners to come forward if they believed their animals had been injured in a similar way.
A police spokesperson said the cuts were clean and straight, and appeared to be have been done with a sharp blade from the likes of a box cutter or razor.
Initially, it was thought the first attack notified to police may have involved an accident with barbed wire, but then the other four injured horses were discovered nearby. It was, said police, clearly a deliberate attack.
They have appealed for information.