NAVAN and Thurles have abandoned four chases scheduled to be run on Sunday.
Navan was due to run three chases on Sunday, but heavy frost has frozen that course.
The hurdle track, set to stage the Grade 1 Navan Novice Hurdle and Grade 2 Philips Electronics Tara Hurdle on Saturday remains raceable.
Manager Darren Lawlor said: "The chase track is more shaded than the hurdle track and will not be able to thaw in time, so we will run an all-hurdle card on Sunday as well as Saturday.
"It now looks like the snow could miss us, but frost is still a concern."
The Irish Form Book Maiden Hurdle, scheduled for Saturday, will now be run on Sunday and will be divided to form a six-race card.
The chase course at Thurles, set to stage the 3m4f Porterstown Handicap Chase on Sunday, is also unfit for racing and the Horse And Jockey Handicap Chase has been abandoned and a hurdle will be divided to complete the card.
No decision has been made on the Porterstown, originally scheduled to be run at Fairyhouse on November 27, or the Molony Cup and the situation is being monitored.
Both chases have been moved to the bottom of the card.