Danny O’Brien is the third prominent Melbourne trainer under investigation for elevated levels of cobalt returned in swabs on horses which raced during the spring carnival.
On Monday, Peter Moody revealed Turnbull Stakes runner-up Lidari had returned a level higher than the allowable 200 micrograms per litre of urine, a threshold introduced last year. 
Moody said in a statement he had no idea how the reading came about and would co-operate fully with Victorian stewards.
On Tuesday, Mark Kavanagh released a similar statement which Racing Victoria stewards confirmed related to Magicool after he won the Listed UCI Stakes on October 4, the same day as the Turnbull Stakes.
RV said three horses trained by O’Brien – Victoria Derby runner-up Bondeiger, Caravan Rolls On and De Little Engine – had tested positive to cobalt.
O’Brien has also issued a statement saying he has no idea how the high readings came about.
Bondeiger and Caravan Rolls On returned the positive tests from pre-race samples before the Derby and the Lexus Stakes respectively on November 1 while a sample from De Little Engine after he won at Ballarat on November 22 contained the higher than allowable level.
Cobalt is an essential mineral nutrient which affects multiple body systems. It occurs naturally and is an ingredient of feed supplements but is toxic at high dosages which prompted the introduction of the threshold.
