Small dog, same rules.

01The law at a glance

Most of these rules apply across Great Britain, with some differences between England, Wales and Scotland, and separate rules in Northern Ireland. Where we say “England”, check the equivalent law for your nation.

02Microchipping

In England, the Microchipping of Dogs (England) Regulations 2015 require every dog to be microchipped and registered on a government-compliant database by the time it is eight weeks old. The keeper must keep the details on the database up to date.1 Wales and Scotland have equivalent rules, and Northern Ireland has required microchipping since 2012 as part of dog licensing.

What this means in practice

• Breeders must chip and register puppies before selling them, with the breeder recorded as the first keeper.
• When you take your dog home, you must update the database to show you as the keeper. The breeder or rescue should give you the transfer details. Check this has happened.
• When you move house or change phone number, update the database. A chip with old details is little use if your dog is lost.
• If your dog isn’t chipped, a local authority or police officer can serve a notice requiring you to chip it within 21 days. Failing to comply can lead to a fine of up to £500.1
• A vet can exempt a dog from microchipping for health reasons with a certificate.

03Collar and tag: the 1992 order

The Control of Dogs Order 1992 requires any dog on a highway or in a “place of public resort” to wear a collar with the name and address (including postcode) of its owner inscribed on it or on an attached plate or tag.2 A phone number isn’t required, but it is sensible to include one. Breaking the order is a criminal offence with a fine of up to £5,000. There are exemptions for some working dogs, such as assistance dogs and police dogs, but not for pet dogs.

Harnesses and the law

The order refers to a collar. Councils’ advice is that a dog wearing only a harness, even with a tag on it, may not comply. The simplest solution for a Chihuahua is to use both:

• A lightweight, well-fitted collar carrying the ID tag, worn on walks and in public.
• A comfortable harness to clip the lead to. Small breeds are prone to tracheal (windpipe) problems, and pressure from a lead on a collar can make coughing and damage worse.

Check the collar fits (you should be able to slide two fingers underneath) and that the tag isn’t heavy enough to be uncomfortable. Slim engraved tags or tags that slide onto the collar suit small dogs well.

04Your duty of care

The Animal Welfare Act 2006 (England and Wales) places a legal duty on anyone responsible for an animal to take reasonable steps to meet its welfare needs. Scotland has equivalent law in the Animal Health and Welfare (Scotland) Act 2006. The five needs are:3

1. A suitable environment, which for a Chihuahua includes warmth.
2. A suitable diet.
3. The ability to show normal behaviour patterns.
4. To be housed with, or apart from, other animals as appropriate.
5. Protection from pain, suffering, injury and disease.

Causing unnecessary suffering is a criminal offence. Since 2021 the maximum sentence for the most serious animal cruelty offences in England and Wales has been five years in prison.

05Control and safety

Under section 3 of the Dangerous Dogs Act 1991, it is an offence for a dog of any breed or size to be dangerously out of control in any place, including in your home and garden.4 A dog is regarded as dangerously out of control if it injures someone, or if it behaves in a way that makes someone reasonably fear it might injure them. This includes a bite to a delivery driver at your door.

It can feel absurd to apply this to a two-kilogram dog, but small-dog bites do happen, especially to children’s hands and faces. The best protection is good socialisation, supervising your dog with visitors, and giving it a safe space when the house is busy.

Local authorities and police can also use Community Protection Notices under the Anti-social Behaviour, Crime and Policing Act 2014 to require owners to deal with problem behaviour, such as persistent nuisance barking.

06Public spaces, parks and the countryside

Local rules

Councils use Public Spaces Protection Orders to set local rules on dogs, such as picking up after them, keeping them on leads in certain areas, excluding them from children’s play areas, or limiting how many dogs one person can walk. Breaches usually carry a fixed penalty notice of up to £100, with larger fines if prosecuted. Check your council’s website; signs at park entrances usually show the rules.

The countryside

• Follow the Countryside Code: keep your dog on a lead around farm animals and wildlife.
• On open access land in England and Wales, dogs must be on a lead of no more than two metres between 1 March and 31 July, to protect ground-nesting birds, and at all times near livestock.5
• Under livestock-worrying law, a dog chasing or attacking farm animals is an offence, and farmers may be entitled to shoot a dog worrying livestock in some circumstances. Recent changes in England and Wales have strengthened police powers and penalties. Small size is no defence: chasing sheep is enough.
• Cattle may see small dogs as a threat. If cattle approach aggressively, let go of the lead only if you are in danger, and get yourself to safety. Pick up a Chihuahua only if doing so won’t put you at risk.

07Dogs in cars

Rule 57 of the Highway Code says dogs and other animals should be suitably restrained in a vehicle so they can’t distract you or injure you or themselves if you stop quickly. It suggests a seat-belt harness, pet carrier, dog cage or dog guard.6 Breaking the Highway Code isn’t itself an offence, but driving while distracted by a loose dog could lead to a careless driving charge, and some insurers may refuse claims.

For a Chihuahua, a secured, ventilated carrier or a small-dog crash-tested harness on the back seat is safest. Never let a small dog ride on your lap or in the footwell, and never leave a dog in a car on a warm day. Cars heat up dangerously within minutes, even with windows open.

08Travelling abroad

Since the UK left the EU, pet passports issued in Great Britain are no longer valid for travel to the EU. From 22 April 2026, EU pet passports issued to pets living in Great Britain are also no longer accepted for travel into the EU.7 A draft UK–EU agreement may bring back reusable pet passports, but at the time of writing there is no confirmed start date.8

Travelling from Great Britain to the EU (current rules)

1. Microchip your dog before, or at the same time as, its rabies vaccination.
2. Vaccinate against rabies. Your dog must be at least 12 weeks old. After a first vaccination, you must wait at least 21 days before travelling.
3. Get an Animal Health Certificate (AHC) from an Official Veterinarian. It must be issued no more than 10 days before you arrive in the EU, and you need a new one for every trip.7
4. Tapeworm treatment is required for dogs entering Ireland, Northern Ireland, Finland, Malta or Norway, given by a vet 24 to 120 hours (1 to 5 days) before arrival.
5. Check entry rules for each country on your route, including limits on how many pets you can bring and any rules on breeds.

Coming back to Great Britain

Your dog needs its microchip, a valid rabies vaccination and the AHC (or other accepted document). Unless you’re coming directly from Ireland, Northern Ireland, Finland, Malta or Norway, it also needs a tapeworm treatment from a vet 1 to 5 days before you arrive. Travel with an approved transport company on an approved route.

Great Britain to Northern Ireland

Travel between Great Britain and Northern Ireland has its own scheme for pets under the Windsor Framework. Check GOV.UK for the current documents you need before you book.

Long journeys are hard on small dogs. Plan regular toilet and water stops, keep them warm (or cool) and in a secure carrier, and think honestly about whether a trusted sitter at home might be kinder.

09Theft, housing and liability

Dog theft

Small, valuable breeds are targeted by thieves. The Pet Abduction Act 2024 created a specific offence of dog abduction in England and Northern Ireland, recognising that pets are more than property. Reduce the risk by not leaving your dog tied up outside shops, keeping your garden secure, varying your walking routes, being careful what you share online, and keeping microchip details current. If your dog is stolen, report it to the police and get a crime reference number, tell your microchip database, and alert local vets, rescues and wardens.

Renting and housing

Private tenants in England can now ask their landlord to keep a pet, and landlords must not unreasonably refuse. See flats and small homes.

Liability insurance

The law doesn’t require pet insurance, but you can be held liable if your dog causes injury or damage, for example by running into the road and causing an accident. Many pet insurance policies include third-party liability cover, and some home insurance policies do. Check yours.