A man was bitten while trying to save his dog from being mauled by another dog in Towcester.
The incident happened as the man was walking his dog in Bickerstaffes Road, Towcester, at about 8.30am on September 4.
He had stopped to untie his dog, which had become tangled in its lead, when it broke free and ran around the corner.
When the man caught up with his dog he found it was being attacked by a second dog, believed to be a dark coloured Staffordshire Bull Terrier. The second dog had the first dog in its mouth.
The man managed to separate them, which resulted in him being bitten on the hand by the second dog.
The first dog sustained a large wound to its neck and required emergency surgery.
Officers investigating the incident would like to speak to the owner of the Staffordshire Bull Terrier.
A woman seen with the dog at the time of the incident was white, in her early 20s, of average build and with shoulder length blonde hair.
Witnesses or anyone with information about this incident are asked to call police on 101 or Crimestoppers anonymously on 0800 555 111.