Harrowing footage appeared to show an XL Bully-type dog being beaten with a shovel in east London - as a rescue organisation warned of a staggering rise in abuse against the breed.
A man has been arrested on suspicion of animal abuse following the incident in Hackney on Wednesday morning.
Footage shared online appears to show a man repeatedly striking the dog - thought to be an American Bully XL - in the head with a large tool in a rear garden at a block of flats.
Nina Willis, who runs the rescue that went to the animal's aid, broke down in tears as she told The Standard of the surge in abuse and abandonment cases she has witnessed since the government announced American XL Bullies are joining its banned breeds list.
XL Bully Rescue and Foundation volunteers were joined at the scene in Hackney by police on Wednesday.
The injured dog was taken to an animal hospital, said Scotland Yard. It was treated for facial injuries, and is said to be in a stable condition.
A Met spokesperson said nobody was at the flat when officers arrived, but a man handed himself into a police station on Thursday and was arrested on suspicion of animal cruelty.
Ms Willis, who runs XL Bully Rescue and Foundation, described the incident as "horrendous".
"I've had nightmares," she said. "It's just the worst thing I've ever, ever had to deal with."
Seval Hassan, one of the volunteers who responded to the incident, added: "I think it's one of the worst things I've ever witnessed in my life. It was a really bad experience.
"Because [XL Bullies] are on the banned list, people are getting rid of them and this is where they're ending up. There are loads more like him out there."
The dog - which Ms Willis has named Zeus - will be rehomed by the rescue once it has been released by police. Ms Willis believes it to be a puppy of around eight months.
Surge in abandonment and abuse since XL Bully added to banned breeds list
Following a rise in attacks by XL Bullies, Rishi Sunak pledged on September 15 the government would ban the breed by the end of the year - something it has now done.
Ms Willis said the pledge immediately sparked a rise in the dogs being abandoned and abused, with some owners threatened they will be evicted if they do not get rid of their dogs.
"Because of the ban a lot of people have been giving [XL Bullies] away for free or very cheaply, so a lot more of the wrong people have got their hands on them," she said. "Which is why we're seeing so much neglect and abuse.
"We deal with this every day unfortunately. But not as bad as this case. This has really, really affected all of us.
"You don't understand the amount of abuse we're dealing with," she added, breaking into tears.
"We seized one from police last Monday that had been chained up outside and beaten. Yesterday we had two cases where they were thrown out of a car and abandoned."
Ms Willis said rescues like hers are now overwhelmed, and it is growing increasingly difficult to find safe places for the dogs.
"We are full," she said. "No kennels are taking them now. Where do these animals go?
"There are hundreds and hundreds of XL Bullies suffering, and being put to sleep, and being abandoned.
"If something does not happen now, we are going to be seeing much, much more of this. This is absolute animal brutality."
On the rise in attacks by the breed, she said: "It is not the dogs, it is the owners.
"These are dogs that are being beaten, severely abused, and when we take them after two days they are a completely different dog.
"They show no aggression, they don't want to harm anybody, they just want you to love them."
The XL bully breed type was developed through the crossing of various bull breeds, including the American Pit Bull Terrier. They are thought to have been around since the late 1980s.
A spokesperson for the Department for Environment, Food & Rural Affairs (Defra) said: "We have taken quick and decisive action to protect the public from tragic dog attacks – with the Environment Secretary adding the XL Bully type to the list of dogs prohibited under the Dangerous Dogs Act.
"From 31 January 2024, owners of XL Bully type dogs have the options of applying for their dog to be added to the Index of Exempted Dogs or take their dog to be euthanised. We are working closely with the police, canine and veterinary experts, and animal welfare groups, as we take forward these important measures."
Anyone with information about Wednesday's incident is asked to call the police on 101 quoting CAD 2303/8NOV.