The man behind the legend of equine racing ambassador Subzero is being treated for cancer in a Bendigo hospital.

Former clerk of the course Graham Salisbury has worked tirelessly with Subzero as part of Racing Victoria's community education program taking the former Melbourne Cup winner around the country.

Salisbury's daughter Nikki provided an update on her Facebook page thanking everyone for their support.

"Just an update on Dad (Graham). Sadly he is back in hospital, he was transferred from the local hospital to Bendigo by ambulance with a temperature of 39.5," Nikki wrote on Monday night.

"They have found that his white blood cells are dangerously low, this is all we really know at this point, hopefully we will know more tomorrow and will update you all as we know more.

"We would like to thank everyone for the amazing kindness and generosity, from something as simple as taking the time to comment with your kind words, or call to check in on how we all are, and keeping us in your prayers, to people sending us extremely generous offers.

"Dad, Mum and I can honestly not thank you enough.

"Please just keep my Dad in your prayers, I would give absolutely anything to take this awful time in his life away from him."

Subzero won the 1992 Melbourne Cup for trainer Lee Freedman and jockey Greg Hall before being retired from racing in 1994 and joining Salisbury.

The striking grey became Salisbury's clerk of the course's horse on Melbourne's metropolitan tracks before being retired in 2008.

Since then he and Salisbury have continued their charity work as racing ambassadors.