Three horses were left wounded and one dead after they were attacked in their fields in Stirlingshire, Scotland.
The horses, which were all stabled at different locations in the Bonnybrigde area received cuts to their bodies sometime between Friday 30 May and Friday 6 June.
One of the horses was so badly injured that the owners had to have it euthanased.
The police have launched an investigation and are urging horse owners in the area to remain vigilant.
Inspector Paul Fleming of Denny police station, said: “To get that close to a horse, a great deal of time has to be spent befriending it.
“The person who has done this is obviously comfortable around horses.”
A spokesman for Central Scotland Police told H&H: “At this time we can give out no further information.
“We are following an ongoing enquiry and are still trying to establish a motive.”
Anyone with information should contact the police on 01786 456000.