Town Police Clauses Act 1847
Under this Act it is an offence for any person in any street to:
let an unmuzzled ferocious dog be at large so that it obstructs or annoys the residents or passengers in the street, or puts them in danger.
To set on, or urge, any dog to attack, worry or put in fear any person or animal.
A dog is not considered to be ‘at large’ while held on its lead and the word ‘street’ is given an extended meaning to include any road, square, court, alley, thoroughfare or public passage.

The Metropolitan Police Act 1839
This Act applies only in the Metropolitan Police District and is a similar offence as the Town Police Clauses Act of 1847. It differs only I that it is an offence to let an unmuzzled dog be at large (no obstruction, annoyance or danger need be shown) and that the public place is described as ANY thoroughfare or public place.

Occupiers Liability Act 1957
This Act refers to the duty of care you have to your visitors, for example, people you invite onto or permit to use your land or premises, whether expressly or by implication. (This includes postal workers, meter readers or anyone else invited or permitted to be there)
You must take reasonable care to ensure that these visitors will be safe to carry out whatever it is you have invited or permitted them to do on your premises or land.

The Dogs (Protection of Livestock) Act 1953
The definition of ‘livestock’ for criminal proceedings under this Act include cattle, sheep, goats, swine, horses and poultry. Game birds are not included, however for the purposes of civil proceedings under this Act, pheasants, partridge and grouse in captivity ARE included.

Under this Act, it is a criminal offence for a dog to be at large (not on a lead) or otherwise under close control, in a field of sheep. Sheep dogs and police dogs are exempted from this provision.

It is also a criminal offence if a dog worries livestock on agricultural land.
‘Worrying’ is when a dog attacks or chases livestock in such a way that it could reasonably be expected to cause injury or suffering, or, in the case of female livestock, abortion or the loss or diminution of their produce.

An offence has NOT been committed if:
At the time of worrying, the livestock were trespassing or
The dog belonged to the owner of the land on which the trespassing livestock were and the person in charge of the dog did not cause the dog to attack the livestock.

This Act is enforced by the Police and not the local authority.

The Dogs (Protection of Livestock) Act 1953 is used alongside the Animals Act 1971.

The Animals Act 1971
This Act places civil liability for damages done by a dog on the keeper of that dog. This includes damage by killing or injuring livestock. The keeper of a dog for the purposes of this Act is the owner OR the person in possession of the dog. If the owner/keeper is under the age of 16, the head of the household is liable.

Important advice to dog owners and walkers.
Whether you live in a rural area or are simply visiting the countryside for a walk, you have a responsibility for keeping your dog under control at all times. All dog should be on a short fixed lead when walking anywhere near livestock. The most well behaved placid dog can become a menace when encountering livestock so do keep your dog under strict control.
Dogs caught worrying sheep are likely to be shot and their owners liable to prosecution and heavy costs.
Owners of pet dogs should be aware that the displaying of any sign which implies that any resident dogs are guard dogs could leave them open to prosecution under certain circumstances and could also imply that they were aware that their animals could pose a risk under the Dogs Act 1871, the Animals Act 1971 or even potentially the Guard Dogs Act 1975.

Any signs on display should be carefully worded. “Caution, dogs running free” would perhaps encourage people to ensure they take care to close gates whereas a sign saying “Warning-dogs loose” may imply that your pet is kept as a guard dog and that it might be dangerous.

The Guard Dogs Act 1975
Many of the provisions of this Act, including sections 2, 3, 4 and 6 are not yet in force, with only sections 1 and 5 applying.
Section 1 of this Act prohibits the use of a guard dog unless a handler capable of controlling the dog is present on the premises at all times, and the dog is under the strict control of the handler unless secured (and is not at liberty to run free). The use of any such dog is prohibited unless a notice warning that a guard dog is present is clearly exhibited at each entrance to the premises.
Section 5 of this Act refers to a breach of Section 1 and will result in criminal liability and a fine of up to £5000.
From a legal point of view, the requirements to have a notice at each entrance point warning that guard dogs are present, in those circumstances in which the word ‘entrance’ has not been defined is somewhat vague. Would a hole in a perimeter fence constitute an entrance point for example? From a legal point of view it is possible.

Guard dog use and the common law.

The common law of tort applies to the ownership of all animals and not just dogs.
Any owner of domestic animals may be liable, on the grounds of negligence for damage caused to third parties by the animals.

Civil liability of the owner depends on whether or not the owner owes a duty of care to the relevant third party and whether or not it was directly foreseeable that the animal would cause the injury suffered.
For example, if a child climbed through a hole in the perimeter fencing and entered a premises patrolled by guard dogs (even those complying with the Guard Dogs Act) and was then badly mauled by a guard dog secured on a chain, the owner and keeper of the guard dog would likely be strictly liable for the damage caused under the terms of the Animals Act 1971 and could ALSO be criminally liable for the aggravated offence under the Guard Dogs Act 1975.

In addition to this, they could be liable for a damages claim under the common law of tort in circumstances where it could be argues that damage was foreseeable, and that the security operator had not checked the security of the perimeter fencing before deploying guard dogs.