Dr Christine Middlemiss urged owners to apply before it becomes illegal to own a bully XL in England and Wales from 1 February.

Owners who do not wish to keep their dogs can have them euthanised and apply for compensation for the cost.

From 31 December all bully XLs must be kept on a lead and muzzled in public.

It will also be illegal from this date to breed, sell, advertise, gift, exchange, and abandon these dogs or let them stray.

Dogs on the exempt list will have to be neutered and microchipped.

The ban was announced in September following a number of attacks involving the breed, and the exemption scheme was introduced for people who already owned XL bullies.

“We want to bring in the certificates of exemptions because we don’t have a way of understanding how many XL bullies there are and exactly where they are,” the UK’s Chief Veterinary Officer Dr Middlemiss told BBC Breakfast.

“It’s great that over 4,000 owners have already registered and we urge the remaining owners who have not registered and want to do so to get on with the process.”

The Department for Environment, Food and Rural Affairs says a majority of exemption certificates have already been issued.

There have been 351 attacks by bully breeds in 2023, according to campaign group Bully Watch.