London —A ban on American XL bully dogs came into effect on Thursday in England and Wales after a spate of violent attacks. Now, owners must apply for an exemption, which requires proof of neutering and liability insurance, in order to keep their pets. All XL bullies must be muzzled and kept on a leash in public.

Before 2021 in the U.K., there were only approximately three dog attack deaths per year. After 2021, there have been at least 23, many of which have involved American XL bullies, according to CBS News partner network BBC News.

“These dogs aren’t cared for by the breeders — they just want money — so from the greed at the start (and) irresponsible ownership in the middle, we’ve got children dying,” Emma Whitfield, whose 10-year-old son was killed by an American XL bully in 2021, said last September.

“My youngest son started comprehensive school last week, and he should have had his big brother showing him the ropes, but he’s had to do it on his own. We’re missing a massive piece of our family,” Whitfield added.

What is an American XL bully?

An American bully is not identified by the U.K. Kennel Club as a specific dog breed. Rather, it is a type of bulldog that is the result of mixing several dog breeds, including Pit Bulls, American Bulldogs, and English Bulldogs.

The U.K. government published guidance to help identify the dogs in which it describes them as having “a muscular body and blocky head, suggesting great strength and power for [their] size.”

Before the addition of American XL bullies, the selling, owning, breeding and abandoning of four other dog breeds was illegal in the U.K.: the Pit bull terrier, the Dogo Argentino, the Japanese Tosa and the Fila Brasileiro.

If someone has a dog that is one of these breeds, it can be taken by police, even if there have been no complaints against it.

Difficult to enforce

U.K. Prime Minister Rishi Sunak pledged to ban American Bully XLs in September 2023 after 52-year-old Ian Price was attacked and killed by two of the dogs. Members of the public attempted to help Price but were unable to get the dogs off of him.

Mark Hobrough, a police chief from the U.K.’s National Police Chiefs’ Council, said the new ban would create “logistical challenges” for officers by sparking an increased demand for kennel space ahead of court rulings on whether dogs should be euthanized.

Over 35,000 dogs in the U.K. are already registered for American XL bully exemptions.