Followers of Satanic cults are being linked with attacks on horses in Sheffield and Derbyshire which have killed at least two animals.
The sadistic wounding of animals in Fox House, Sheffield, and Derbyshire's Peak District villages have upset farmers and locals so much that police spent the weekend staking out problem sites, waiting for attackers to strike during the mid summer solstice.
Recent incidents include one when a young horse was disembowelled after having its stomach slashed in Eyam, where a foal was also drugged and attacked.
Another colt at Fox House was 'drained' through cuts in its legs, which police suspect was to obtain blood for religious It is thought horses' blood can be sold for £60 a pint, senior South Yorkshire police officers say.
The attacks are often accompanied by gothic calling cards left in the fields, including circles or pentangles made from stones or branches.
Police also have evidence of sex attacks against some of the horses.
About 16 police officers from Derbyshire and South Yorkshire and a number of RSPCA officials mounted a three day surveillance operation at Fox House, Eyam, Stoney Middleton and Curbar, which ended yesterday without an arrest being made.
One horse owner from Chesterfield, who does not want to be named, said: "When me and my girlfriend were told why this might be happening, it put the fear of God into us.
"We've been camped out in the fields ourselves, because we've been so frightened for the horse."
There have been increasing incidents of 'horse ripping' attacks in Britain and on the continent in the last 10 years, particularly in Germany and Scandinavia.
There have also been similar attacks in Nottinghamshire and Barnsley.
Reasons for the brutality include Satanic worship and sexual perversion. There has never been an arrest made in connection with such an attack in this country, police say. Supt Clive Davis said: "The locals are really spooked by what is going on.
"We don't know what religious or spiritual significance the affected sites have, but these are not random attacks.
"We have taken this seriously enough to mount a very big operation over the solstice weekend, and it is disappointing that we didn't get a result.
"Although we have had to scale the operation down, we will continue to support the community there.
"We have to respect other religions and beliefs, but we can't allow the sort of incidents that have gone on to continue."