Top Melbourne Cup hope Red Cadeaux is at the centre of a virus scare that has resulted in one horse being placed in isolation at the Werribee quarantine centre.

Red Cadeaux, last year's Cup runner up, had been stabled in the same barn as the affected horse until it was removed.

Owner Lloyd Williams revealed on Tuesday his horse Hartani, who is not entered in any spring races, had come down with a virus.

Williams said the connections of Red Cadeaux had reacted with understandable anxiety over the situation, but despite the ability for viruses to spread quickly through stables, their horses had so far shown no sign of infection.

Robin Trevor-Jones, the travelling foreman for Red Cadeaux's trainer Ed Dunlop sent Red Cadeaux out for his scheduled light work on Tuesday and seemed unworried.

But representatives from other stables staying in the same quarantine compound have expressed concerns, although no other horses have shown symptoms.

There are no concerns for the bulk of the internationals, including the equal Cup favourites Dunaden and Americain, who are stabled in a separate compound.

Red Cadeaux and his Cup jockey of last year and for 2012, Michael Rodd, reunited for the first time in 12 months on Tuesday, the jockey taking the horse on a two-lap workout at Werribee, completing the job with 1200m in slower than even time.

"He felt fantastic," Rodd said.

"He's bigger and stronger than last year, it's very noticeable when I sit on him that he feels a lot wider."

Red Cadeaux is regarded by many as the horse most favourably treated by the handicapper, particularly when compared to Dunaden, the horse that beat him by a nose in last year's Cup.

On that run, Red Cadeaux is 2.5kg better off against Dunaden and Rodd has no doubt the horse has improved - and so has his knowledge of him.

"I was told to put a pen through his last run when he was third at Newmarket, but his previous four runs in Europe this time in were all very good.

"But perhaps the big thing is that I understand him better now.

"Last year I got to the front too soon because he caught me by surprise when he sprinted so quickly."

Dunlop arrives in Melbourne On Wednesday and has scheduled a gallop for the horse on either Friday or Saturday.