The three-year-old won the hearts of racing fans last summer after winning four Group One races.
Roaring Lion won at Sandown, York, Leopardstown and then Ascot in the Queen Elizabeth II Stakes.
Trainer John Gosden and connections decided to retire him to stud and he has recently been in New Zealand at Cambridge Stud.
Roaring Lion was released from quarantine on Saturday but showed symptoms of colic but he is now recovering at Cambridge Equine Hospital after successful surgery.
Stud CEO Henry Plumptre told www.
nz: ‘We want to act in the best interests of (owner) Sheikh Fahad and our shareholders.
Following major surgery, we feel it is appropriate to withdraw the horse from service with all shareholders being fully refunded.
‘Our best-case scenario is that Roaring Lion makes a full recovery and can be returned safely to the UK.
While everyone at Cambridge Stud is shattered, we feel the obligation to Sheikh Fahad, David Redvers and our shareholders is important.
‘It is a massive blow to lose Roaring Lion like this, but his ongoing welfare is now our prime concern.’
High expectations for unbeaten Autumn Stakes winner
Aintree the aim for Scottish National third
Nagano Gold has an opportunity to put...