Two dogs caught worrying sheep at a Lanark farm on Sunday were shot dead by the farmer.
Two sheep were killed in the attack, by a husky and a Staffordshire terrier.
Police investigations to trace the owner are continuing.
The attack, on a farm on the outskirts of the town, is the latest in a list of such incidents this summer.
Two dogs were destroyed in a livestock attack on a Thankerton farm, and there have been a number of dog attacks leaving sheep dead in Carluke. Earlier this month, three pet lambs were killed.