"The owner was just holding onto her dog's tail - she was too scared of being attacked.
"Eventually, exhausted, I got it in a chokehold and it lost its grip on my dog."
The woman said that as Alfie was released, a woman with a child in a stroller appeared.
"It must have been terrifying for them. I was holding my dog together with my jumper because he was gouged open and I was covered with blood. Another woman came along with her dog and she ran off screaming when she saw the carnage. She obviously didn't want the same to happen to her dog.
"Luckily there was a road worker in the area who took the details of the lady whose dog attacked Alfie and then he took us to the vet in his truck."
The two-year-old Jack Russell's lower jaw was fractured in two places and it received puncture wounds over the front half of its body, a large gash down one side and incisions under a front leg.
"He's terrified of other dogs now and has lost his appetite. I have to force him to eat. I'm feeling devastated and I don't think I'll want to take him out in public again. My nerves are shot and I'm terrified even for my own safety. I grew up on a farm and have always been around animals and I've never seen violence like that from an animal.
"It's not the dog's fault, it's the owner's. It was negligence and ignorance. In the right hands that dog would perhaps have become a normal decent animal."
The woman said the pitbull's owner had offered to pay the vet bills "which I really appreciate".
"The vets and dog ranger were very supportive. The work the vet has done is brilliant and they did everything they could to fit me in when they already had dogs undergoing emergency surgery.
"I just want to highlight that people need to be cautious around dogs they don't know. What if that had been a child instead of my dog? People need to know their responsibilities if they own a [menacing] dog and make sure they are muzzled in public."
Whanganui District Council compliance team leader Warrick Zander said following a dog attack at Kowhai Park on Friday, a pitbull terrier cross was impounded and an investigation is currently under way. He said a decision is yet to be made on whether the owner will be prosecuted.