Melbourne Cup winner Subzero has made considerable improvement and is off the danger list at the Bendigo Equine Hospital.

His owner and constant companion Graham Salisbury, who rode Subzero as his clerk of the course mount for many years at Flemington, said the gelding, who turns 31 on Thursday, made a giant leap forward overnight.

Salisbury said Victorian Equine Group's Sarah Jalim had reported Subzero was bright with his temperature improving.

"They were very worried about him because he hadn't been passing any manure, but he's passed overnight," Salisbury told RSN927.

"He's still a little way off but he's going forward and she said that's the main thing.

"Finding that length-and-a-half has got him off the danger list."

Salisbury said it had been a trying period with Subzero fighting off a bout of colic, being treated for kidney issues as well as peritonitis, all three potentially lethal for horses.

He said the prospects of Subzero returning home to his Heathcote property were increasingly likely.

"When he went there, there was very little hope of him coming back, but now there's every chance that he'll be coming home," Salisbury said.

"When he's ready I'll pick him up and when he gets home, in his own environment, he'll find another couple of lengths.

Subzero won the 1992 Melbourne Cup and joined Salisbury in 1994 when he retired.

At the end of his clerk of the course duties, Subzero became a racing ambassador and regular visitor to children's hospitals and nursing homes and in 2014 was honoured by the Australian Racing Hall of Fame for his services to the community.