Aux Ptits Soins has been ruled out for the season with a hind suspensory problem.
"It's a bit of a strange injury, it's more common in show jumpers," said Skelton. "It's a hind suspensory. Usually in racehorses the problem is at the front end.
"It's not career-threatening or anything and he's only seven, so he won't be old for a stayer when he returns."
It is another blow for Hales and Skelton who lost the promising Captain Forez a few weeks ago.