A pregnant horse died after suffering massive internal injuries from an attack which killed her unborn foal.
Now, her owners are offering a £1,000 reward for information leading to a conviction.
The 19-year-old chestnut mare, Persian Dream, was attacked with a blunt instrument.
The distressed foal died within hours of the crime’s discovery and the mother died from shock and internal bleeding.
Owner Graham Worrell runs Prospect House Farm in Gate Burton, Gainsborough, with his wife Gill and son Rupert, who have all been left heartbroken.
The family has bred horses in the area for nearly 50 years.
“She was so horrifically damaged that the attack defies description,” said 67-year-old Mr Worrell.
“I’ve been breeding horses very successfully since I was 18 and I’ve never known anything like this.
“It was just unimaginable, I hate to think of her suffering so much. It was just plain murder of a defenceless animal.”
‘It was murder of a defenceless animal’
Rupert Worrell, 41, said: “Persian Dream was such a calm mare she would have allowed anyone to lead her.
“They certainly picked the animal which wouldn’t resist an attack. It was like a satanic sacrifice.
“That’s why we’re offering the reward. Whoever did this needs to be caught before they do it again.”
Police believe that the mare was attacked with a blunt instrument at some time between 10pm on Thursday, May 3, and 6am the following morning.
She was found in the field off Clay Lane in Gate Burton and died the following day despite the efforts of specialist vets at Market Rasen Racecourse.
Lincolnshire Police’s wildlife crime officer PC Nick Willey said: “This has been devastating to the owners, who are very upset that their much- loved animal has died so needlessly.
“Fortunately, such crimes are rare in the county and we are asking the horse-owning community to be extra vigilant.”
Lincolnshire Police spokesman Dick Holmes said: “There is currently no evidence to support the rumour or suggestion that the cruel abuse of this horse was part of some kind of satanic ritual.
“We are approaching this investigation with an open mind. All leads will be pursued.
Police are appealing for any information and witnesses to suspicious near the field off the main A156 at Gate Burton.
Call 101 with incident 242 of May 5 or Crimestoppers anonymously on 0800 555111.