Control your dog so that it does not scare or disturb farm animals, wildlife or other path users. In general dogs must be kept in sight and under close control and should not be allowed to stray off the path.
Close control broadly means either on a fixed lead, walking to heel or with reliable recall.
If you meet farm animals while out walking it is probably best to keep your dog on its lead and leave as much space between your dog and the animals as possible (don't worry too much about keeping to the line of the path in this instance). Sheep will often move away but cows can be very inquisitive and suspicious of dogs, especially when they have their calves with them. If cattle do start to act aggressively, let your dog go and allow it to run to safety while you leave the field as quickly as you can.
A loose or out-of-control dog could cause a pregnant ewe to miscarry or cause a newborn lamb to be separated from and rejected by its mother. Landowners have the right to destroy a dog that is attacking or worrying their livestock, so please do everything you can to keep your dog safe and away from livestock when out walking. In addition if dog owners are convicted of allowing their dog to attack livestock they can be fined up to £1,000.
In some areas your dog can enjoy greater freedom and be safely let off of the lead. Always be aware of other users and make sure that you do not lose sight of your dog. Conditions can change very quickly and you need to have good recall if you do intend to let your dog off the lead on a public path.