Over the weekend Mountbatten, a 10-year-old Irish mare, became the first horse to be killed outright in more than 30 attacks that have terrorised Hampshire and neighbouring counties.
The attacks seem to be gathered roughly into two clusters 40 miles apart, one in Hampshire, the other in Buckinghamshire. Their frequency is increasing.
Mountbatten was found by her owner with her head lying against the stable door, a large gash on her neck, and her genitals and hindquarters cut.
Fiona Broderick, daughter of the owner, Robert Broderick, said: 'How anyone could do this to a horse is beyond me. My father loved her tremendously. He is absolutely distraught.'
In the past nine months, more than 30 horses - 22 in Hampshire - have suffered mutilation and sexual assault. Some have had to be put down. Horses and ponies have been cut with Stanley knives, had broomstick handles and posts inserted in their vaginas and had battery acid thrown over them.
Police believe there may be a sexual motive for the attacks but are remaining open-minded. They say they are linking the attacks, but have no idea whether the same person or people are responsible. 'It could be a pervert, a psychopath, an animal hater, a hunt saboteur or someone with a grudge,' said a spokesman, adding that there appeared to be no clear pattern to the attacks.
'The only pattern is the inconsistency. There doesn't seem to be any rhyme or reason, no pattern of time or places, no consistency of victims. Sometimes he attacks mares, sometimes it is geldings or stallions,' he said.
A reward of pounds 1,000 for the capture and conviction of the attacker, dubbed the 'horse ripper', has been offered by the International League for the Protection of Horses.
Two days before Mountbatten was killed, Bluey, a five-year-old mare kept at Speen, near High Wycombe, Buckinghamshire, received a 6in wound to her genitals after a knife attack.
Earlier last week another mare had part of her foot hacked off with an axe at Princes Risborough, Buckinghamshire.
Police in Hampshire, have asked experts at Leicester University to draw up a psychological profile of potential suspects.