Zoe Williams says the dog attacked her Labrador, Charlie, before attacking her partner Rob, when he tried to separate them.
He received injuries to his hand and knee, and the dog had to have extensive surgery to his leg.
Since the attack, Charlie has had pins into his leg, which was broken.
The dog owner is described a black male, in his late-twenties or early thirties, with short curly black hair. Zoe says the dog was a light brown pit bull-type breed, with a white mid-line.
Nottinghamshire Police released this statement:
Nottinghamshire Police received a call at around 2.30pm on Tuesday 16 May 2017 of dog attack in a forest area off Hucknall road in Old Basford.
It was said that a dog had attacked the victim's dog and as he tried to intervene, he too had suffered cuts to his hand and knee. The injured dog was taken to the vets and the incident was reported around two hours later.
Officers are investigating and are making inquiries.
(ITV - May 21, 2017)