Members of the public had to prise the animal's jaw open after it bit the pensioner as she tried to protect her own dog.
The dog's owner, mum-of-four Claire Chambers, shouted foul-mouthed abuse at people who went to help the elderly woman.
Chambers accused one man of being a "grass" when he contacted police and said "I will rip your head off" to another woman.
The 33-year-old was given a suspended prison sentence over the incident in Wakefield on July 26 last year.
The victim, a neighbour of Chambers, entered the field with her small black dog.
Soon after Chambers shouted to the woman to pick up her dog as Bella ran towards her.
Miss Gilmore said Bella latched on to the woman's hand and bit down as she went to pick up her dog.
Bella then tried to bite the other dog by the neck but got hold of its collar.
The woman screamed and was helped by two men who threw water over Bella and pulled Bella's jaws apart.
Miss Gilmore said Chambers was apologetic at first but became verbally abusive when someone suggested the dog should have been on a lead.
She continued to be aggressive when paramedics were called to the scene, telling people: "I will take all of you on."
Chambers was arrested and claimed she did not believe her pet was responsible for causing the injuries.
She also claimed the incident happened when the victim's dog attacked Bella
Chambers, of Denhale Avenue, Flanshaw, pleaded guilty to being in charge of a dog dangerously out of control, causing injury, and threatening behaviour.
Kate Bisset, mitigating, said Chambers was sorry for what had happened and had kept her dog muzzled and on a lead since the incident.
Miss Bisset said Chambers had been diagnosed with a mental health condition which led to her being abusive when confronted by others after the incident.
Chambers was given a four-month prison sentence, suspended for two years, and ordered to take part in a 20-day rehabilitation programme.
Judge Tom Bayliss, QC, said: "You knew the dog in the past had behaved aggressively towards other dogs and you allowed it to just get out of control and attack this woman"