You should keep extra care when in the countryside with your pet during the lambing season. Keep your pet on a lead in the public rights of way where there are pregnant sheep present.
Sheep worrying is a problem for the sheep farmer. It is major problem during the lambing season which is usually from December to April.
If your pet chases the sheep it can injure or cause death. Sheep are very nervous and if they sense danger they run in a pack. If a sheep is chased or runs while pregnant the ewe could abort their lamb. This is a big loss for the farmer. The sheep can develop a fear of dogs which is a problem for the sheep farmer who uses the trained sheep dog to herd their flock.
If sheep are worried by a dog they can become separated from their lambs. If it is a very young lamb it could die from the hunger and cold.
Also if a sheep is in the process of giving birth and is interrupted it could lead to the death of the lamb.
Any breed of dog big or small trained or untrained can be involved in sheep worrying. Dogs still have their basic instincts. The chase instinct can be triggered by the slight movement of an animal. Once your pet becomes transfixed on the chase its difficult to get them back through recall. You just have to hope that they become bored, see something else that interests them or tire themselves out. If a farmer sees your dog chasing his sheep it could be a big problem for you and your dog. Prevention is the best port of call.
In some places it is legal for farmers to shoot and kill dogs that are seen trespassing on their land. Some trigger happy farmers do not need much prompting to shoot and kill your beloved pet.
The dog owner is liable for any damages occurred during sheep worrying or kill. Even if your pet is a saint at home if it joins a group of dogs they could do alot of damage.
Also you don't want be held responsible for someones else's dogs attack. When a farmer finds a dead sheep they want to find a culprit. If you are known for having a dog off lead in a sheep area you could get the blame and face the wrath of an angry farmer.