© Tony BartlettTests are continuing to determine how 21 quarter horses died on the Gold Coast.
The animals started dying late last week at Kooralbyn, in the Gold Coast hinterland.
Dr Rick Symons says hendra virus has been ruled out and blood tests from ill and dead horses have shown nothing else.
Authorities are now waiting for the results of test on samples taken during autopsies.
Dr Symons says the property is being searched for poisonous plants, and two horses, which were still healthy, have been moved away but are being monitored.
The owner of the quarter horses, Steve Hogno, says if it turns out to be a poison, he's not sure why he would have been targeted.
"Deliberate poisoning has been suggested, we would very much hope that that's not the case," he said.
"I couldn't imagine anyone doing that to lovely animals, but they're certainly doing tests, they've broadened out the scope of testing.
"All the tests are not in yet, of course, because they were done over the weekend and it does take some time."
Mr Hogno says all the horses were young and the basis of his future racing and breeding stock.
He estimates his losses at $200,000.
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