It happened sometime between about 17:00 and 17:30 last Wednesday, 10 October around the Chouet area, which is popular with dog walkers and others.
Guernsey Police said they “are appealing for information in relation to an incident.”
It was reported that a black and white Bull Mastiff dog, or similar breed, bit a smaller dog.
In particular Police Constable 90 Robinson, who is investigating, would like to speak to “a female wearing sports clothing who is believed to be the owner of the Bull Mastiff.”
Anyone with any information is asked to contact PC Robinson on 725111 or Crimestoppers anonymously on 0800 555111.
Pictured: File image.