After watching CCTV footage of the incident caught on camera at a nearby house, Mr Gregory, said: "We are devastated and heartbroken, and my mum is traumatised by what happened.
"I'm surprised she never had a heart attack. It must have been so frightening and shocking to see.
"I could see the dog going berserk before my mum and Jasper came into shot - it was jumping around as it was trying to break free from the owner.
"My mum kept to the inside of the pavement but as the dog tried to bite Jasper, he started barking at the other dog.
"At this point, you could see them both pulling on their leads but the other owner was completely overpowered by her dog, who eventually detached itself from its collar.
"He sunk his teeth into Jasper and was just shaking him around like a ragdoll. It was really difficult to watch.
"My mum was trying to pull him back, but then Jasper detached from his collar too. He bolted down the road and the other dog went after him.
"The dog is not safe to be out without a muzzle, it could attack a child next."Or a child trying to defend it's own pet.
But if you're wondering why the police aren't involved, you're not alone.
The RSPCA don't miss a trick, though:
The RSPCA Cymru said it is "vital" owners do all they can to ensure their dogs are under "proper control" at all times.No shit, Sherlock!
A spokesman, said: "Our thoughts are with the injured dog and their owners at this time; and we of course wish the dog a speedy and full recovery from the reported injuries.
"Sadly, dog-on-dog attacks can prove fatal and it is vital owners do all they can to meet their responsibilities, and ensure their dogs are under proper control at all times.
"It is vital owners understand the circumstances likely to lead to their dog being aggressive and also the signs of potential aggressive behaviour in their dogs, and how to respond.
"Keeping dogs on a lead in appropriate places can also reduce the risk of incidents associated with aggressive behaviours.
"We urge anyone concerned that their dog may be aggressive to contact a properly qualified professional behaviourist, with the appropriate knowledge, skills and experience, for help and advice."And I'm sure the RSPCA would be happy to recommend one. Probably one who works for them!