Your dog must have proper identification with a suitable collar and clearly displayed tag. Go to ID Tags and Microchipping for further details.
Dogs must be kept under control at all times.
Owners can be prosecuted for allowing dogs to bite people or attack other animals.
Special care must be taken in areas where children play.
If a dog has a suspect temperament, keep it on a lead and muzzle it when in public.
Keep dogs in when the postman and refuse collectors are due.
Make sure fencing is adequate and dogs cannot escape.
All dogs should be on leads on roads.
Dogs must never worry livestock. Even letting your dog walk in the same field as farm animals may be considered as "worrying". The farmer is entitled to kill your dog if it is worrying livestock.

Dangerous Dogs

Information on Dangerous Dogs including a list of types of dogs prohibited in Britain, is available from the government Department for Environment, Food & Rural Affairs (DEFRA) website.

The DEFRA Control of Dogs website also covers:

control in public places
dogs and trespass
dogs worrying livestock
guard dogs and other legislation on the control of dogs