The canine, which was not on a lead, set upon the animal at about 10.45pm near New Earswick Sports Club on May 13.
Walnut, the eight-year-old cat, died following the attack.
Its owner, a 19-year-old man from York, suffered injuries to his hands as he tried to prise the dog's jaws apart to release his pet.
He was taken to York District Hospital for treatment of his wounds and was later discharged.
Police have today (Friday) issued an appeal for information, as they try to establish the circumstances surrounding the attack.
The dog's owner is described as being a white man, about 5ft 8ins tall, of average build.
He was in his early to mid 30s, with short brown hair, and was wearing a green or black parka-style coat with black jogging bottoms.
The dog, described as being medium to large in size with short hair, was of stocky build, wore a plain collar and had shades of brown in his fur.
Anyone with information is asked to call police on 101, quoting reference number 12180083903.