On a visit to one of Upper Clydesdale's many hillforts a couple of years back, I sought out a Bronze Age cairn close by. The top couple of feet had been ripped off, a fair number of dead sheep and lambs laid in, then the stones put back on top.
There are hillfox problems in many upland areas like mine where many sheep and lambs are killed far from roads and access tracks. Farmers are left with many rotting, half-eaten sheep carcasses to dispose of. I'm certainly not defending the damaging of ancient monuments but some agricultural workers might well not realise that the pile of rocks they used to dump dead lambs under is not an old field clearance heap but an ancient burial cairn.
The people who sunk their pets into Kinrive East might have just thought it was an old field clearance cairn. Or maybe not thought at all...