The revelation is a bittersweet consolation for Clayton Bay's Julie Jackson who is struggling to cope with the violent end met by six other miniature horses which were slain at the weekend.

Fleurieu Hill Superintendent Rob Williams attended the Jackson property on Saturday morning, about 80 kilometres south of Adelaide.

In all, nine miniature horses valued at $10,000 each were housed in the remote stable but only six were killed in which Supt Williams said police were treating as a targeted attack.

"To find this house, you would need to know where it is and roughly the lay out, especially at night," he said.

"When I spoke to the owners, that stall, the one with the three horses, the door is difficult to open so that could have spared them.

"When I was at the property, the other horses were so friendly, so very friendly, they are more like a family dog than a horse."

It is believed the horses were killed some time between Friday night and Saturday morning when the gruesome discovery was made.

They were killed with what police have described as a "large knife". Supt Williams said he was unable to say whether or not the weapon had been recovered.

"We are following a couple of lines of inquiry but there is no clear suspect at this stage, other than to say we're considering a targeted attack," Supt Williams said.

"The Finniss-Clayton Road is a quiet road, especially on a Friday night so we're urging anyone who might have seen a car looking down driveways or anyone acting suspiciously to come forward with that information."

If caught, the offender/s would be charged with property damage under the Criminal Consolidation Act.

The maximum penalty is 10 years jail.

The family is considering offering a reward for any information which leads to an arrest. Information can be given to police by phoning Crime Stoppers on 1800 300 000.