Owners Lloyd Williams and son Nick are angry their Melbourne Cup contender Amralah has been forced out of the race because of what they say is the wrong veterinary advice.

The highly regarded imported stayer was sent to a Ballarat practice with a stiff neck after his win in the Herbert Power Stakes on October 10.

"He had a cortisone injection in his neck," Nick Williams said.

"They gave us advice that it would be out of his system in 14 days and he's positive."

"You go to experts, spend a year trying to get a horse ready and it's only by chance we had him tested.

"Can you image if he had run and won.

"It's a horrific circumstance."

Amralah was safely in the 24 horse-field before the test showed he was still positive to the treatment.

His withdrawal enabled stablemate The United States to make his way into the field.