Australasian Oaks winner Abbey Marie is responding to treatment after being struck down by a mystery illness.

Trainer Mick Kent said the filly spiked a seriously high temperature in the spelling paddock but it has now come down after an anxious couple of weeks.

"If she could have five days with no temperature I'd be pretty happy," Kent said.

He said the filly had returned from her victory in Adelaide on May 7 and spent five days at his Cranbourne stable and another 10 days in the paddock before spiking the temperature.

When she failed to respond to a course of antibiotics, Kent sent her to the Werribee veterinary clinic.

A thorough examination of the filly has been unable to find the source of the temperature spike.

"They've had all the specialists go over her," Kent said.

"We've done spleen biopsies, two peritoneal taps, checked her ovaries, her guttural pouches, her lungs, we've done a tract wash.

"It's some sort of bacterial infection and the suspicion is an abdominal abscess.

"We took her off the antibiotics for three days to see how she went and she spiked a temp again, so they've put her on the big guns and she's responded.

"She's been sick a long time but she looks quite well."

Kent said once Abbey Marie was given the all-clear she would have a good break and hopefully be back for the latter part of the spring.

"The big plus is her temperament," Kent said. "She just copes with it all."

The unbeaten Abbey Marie won the Group One Australasian Oaks at just her third start.