A horse is in a serious condition after being stabbed in the neck as it grazed in a Sunderland field
The horrifying assault happened between 10am and 6.30pm on Wednesday, January 13, off Saint Lukes Road.
The injured horse is a five year old cob called Lloyd, and officers are carrying out enquiries to identify those responsible.
Neighbourhood Inspector Lisa Laverick said: "We know this incident will cause concern to the local community, in particular those people who own horses and I would like to reassure them we are doing everything we can to identify those responsible so that appropriate action can be taken.
"At the current time we do not know what kind of motive this person has had and what they were trying to achieve by carrying out this act. However it is clearly very concerning behaviour and officers will be working with local horse owners.
"If anyone has any information about the incident I would urge them to get in contact with us."
Ryan Sinclair, 22, who lives nearby, told the Echo he had heard neighbours talking about what happened.
The Nissan-worker said: "I know that one horse was hurt in the back of the neck. Someone in the house mentioned it. It happened yesterday.
"It's obviously not nice at all."
Mr Sinclair added: "Different people just put their horses in the field, we don't know who owns them."
A 74-year-old woman, who lives in St Luke's Road, said: "I'm shocked. This is the first I've heard of it. It's a shame isn't it. I hope the horse pulls through.
"My daughter lives up the road and she is really concerned about the horses there. They just put them there and don't look after them."
Any witnesses should contact Northumbria Police on 101 quoting reference 609 140116 or Crimestoppers anonymously on 0800 555 111.