Paul Deveraux was walking the Mastiff on a 30ft lead across unlit playing fields off Harrison Drive, Worksop, at 6pm, on November 22.
“The owner of the Schnauzer saw his dog being mauled,” said Kate Beardmore, prosecuting.
“It clearly had its jaws around the smaller dog and was shaking it violently.
“He pulled it from the dog’s jaws and was bitten on the hand. His dog was seriously injured and he was bleeding.”
Deveraux appeared and said: “He looks all right. Take him to the vet and I will pay for the bill.”
They exchanged details, but while the Shnauzer’s owner was in A&E at Bassetlaw Hospital, he received a phone call from the vet to say his dog had died from its injuries.
Deveraux told police he only became aware of the attack on the dark playing field when he heard the Schnauzer yelp and the attack was over in seconds.
Justin Atkinson, mitigating, told the court there had been no previous incidents and that Deveraux, a single factory worker, was a fit and proper owner.
Deveraux, 49, of Williams Street, Langold, admitted being in charge of a dog that was dangerously out of control when he appeared at Mansfield Magistrates Court on Thursday.
District judge Andrew Meachin made a contingent destruction order, which means the dog must be kept muzzled and on a lead, and will be destroyed if it attacks again.
Deveraux was visibily relieved to learn his dog would not be put down and told the court: “He is my life.”
He was fined £250 and ordered to pay compensation of £150, the vet’s bill of £356, and costs of £85.