The owners of six miniature show horses slaughtered in their stables say the killers are “scumbags” and “evil doers”.

Julie and Mel Jackson, who run a breeding and show stud at Clayton Bay, 70km south of Adelaide, believe the attackers deliberately targeted their horses but don’t know why.

They have appealed for any other horse owners or breeders who have received threats to contact police.

“Your information, however much you think insignificant, could add to the volume of evidence already on hand and help us put away the evil-doers for a very long time,” they said.

“The perpetrators are facing a jail term of up to 10 years for this crime, maybe more if the court is convinced that others have received violent threats from the same scumbags.”

The six horses had their throats slashed some time between Friday night and Saturday morning.

Three other horses in the same stables were not harmed.

A $100,000 reward has already been posted, with a further $10,000 also being offered by a local radio personality.

Premier Jay Weatherill has described the attack as a distressing and awful crime and says those responsible should face the full weight of the law.

“We cannot have people who commit crimes of that sort on the loose,” Mr Weatherill said.

“One only imagines what risk they pose to the broader community if they can do such a horrible thing to such defenceless animals.”

The Jacksons say they have been comforted by the messages of support they have received since the attack.