North Yorkshire Police told Yorkshire residents to "take extra care" on Bank Holiday walks due to the possibility of livestock in country fields.
In a social media update, the force said: "With lambing season coming to a close, it's important to be aware of the consequences of a dog attack on sheep.
"Any dog, no matter how well behaved, can quickly get out of control when off the lead around livestock.
"Our message to you is really simple – keep your dog on a lead, and under control."