The woman in her 60s was walking her dog on Strongwood field in the Eastfield area.
Another dog approached and attacked the victim’s dog, causing cuts and lacerations.
During the attack the victim was also knocked to the ground, causing her to break her arm.
It happened at 9am on Wednesday, 19 December 2017.
Officers are conducting enquiries and are requesting the public’s assistance to help determine the full circumstances surrounding the incident.
The attacking dog was described as grey/brown in colour and its owner was a man, about 5ft 6ins tall, wearing a flat cap and dressed in grey.
Anyone with information that could assist the investigation should contact North Yorkshire Police on 101, select option 2, and ask for Joseph Schramm. You can also email [email protected]
If you wish to remain anonymous, you can pass information to Crimestoppers on 0800 555 111.