Police are warning horse and stable owners to be on the alert after reports of horses having their mane and tails cut.
The latest case happened in a field near Town Drove, Quadring, where a horse is thought to have had part of its tail cut at about 11am on Saturday.
Earlier in the week, two horses had their manes and tail hair cut while they were loose in a field in West Pinchbeck.
The latest incidents happened more than seven months after a 19-year-old horse called Joe was stabbed while in his field in Holbeach.
A Lincolnshire Police spokesman said: “We are asking stable and horse owners to be vigilant by carrying out regular checks on their properties and surrounding areas.
“They should report any suspicious activity to us on 101.”