Trainer Lucinda Russell says One For Arthur is recuperating well following a heart scare at Haydock on Saturday.
Racing in the Unibet Grand National Trail, the 2017 National winner pulled up with a fibrillating heart.
Dr John Keen from the Royal Veterinary School in Edinburgh checked the 11-year-old on Monday and a scan showed no physical issue with his heart.
Dehydration is believed to be the cause of the problem and doctors have fitted a 24-hour ECG monitor which will be analysed to see if they have any reason to believe further issues could surface.
However, Russell says her charger is okay for now and there are no immediate concerns.
“Arthur’s heart is in perfect rhythm and there is no atrial fibrillation any more,” she said.
“Dr Keen did a total scan and checked all the valves and the whole structure of the heart and that was found to be very good.
“Obviously we want to know the reason for it and to stop it happening again going forward. The conclusion the vets have come to is that it was a dehydration issue.”