Last year's runner-up Marmelo and Godolphin's Ispolini have been ruled out of the Melbourne Cup after failing veterinary scans.

After showing signs of soreness, Marmelo had been referred to the University of Melbourne Equine Clinic to undergo a standing CT scan which indicated an incomplete fracture in his near fore cannon bone and another in his off hind cannon bone.

Racing Victoria stewards studied an RV veterinary report and one from trainer Hughie Morrison before ordering the horse's withdrawal on Wednesday night.

Under the conditions of the race, a horse must be considered fit to race on Saturday, the day final acceptances are taken for the Cup three days later.

The CT scan on the Charlie Appleby-trained Ispolini indicated pre-fracture pathology within the horse's right front cannon bone.

Both trainers have been told of the decisions.

The withdrawal of Marmelo leaves Hugh Bowman without a ride.

Marmelo, who won the Prix Kergolay in August to confirm his third trip to Australia, finished second in the 2018 Cup to the Appleby-trained Cross Counter who has returned to defend his title.

Ispolini was a recent winner of the German St Leger.