Mysteree returned a dirty scope following his disappointing effort when pulled up in the Welsh National at Chepstow.
The 10-year-old was among the leading fancies for the Grade Three but was struggling from some way out, with trainer Michael Scudamore eager to put a line through that performance.
He said: "Robbie (Dunne, jockey) said he was not happy with him from an early stage. When he pulled him up he was struggling for air.
"The vets there scoped him straight away and as soon as they put the scope down, his lungs were full of thick, heavy mud. It was almost like he was suffocating and couldn't breathe.
"He has come back 100 per cent and is fine and well. We will reassess.
"We have got the Eider Chase (Newcastle) and maybe we might go back there, or there is the Grand National Trial at Haydock in the middle of February."
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