Guest turned to training after winning the rain-hit 2001 NationalTrainer Richard Guest, a former Grand National-winning jockey, could still face a ban from racing over animal cruelty claims.
The Horseracing Regulatory Authority (HRA) has announced it will hold its own hearing following a court case.
Guest, who won the National on Red Marauder in 2001, was given a two-year conditional discharge by Durham Magistrates' Court in November.
He admitted causing unnecessary suffering to the horse What's A Filly.
The trainer, along with two employees Richard Dalton and Louise Tidman, were given two-year conditional discharges after What's A Filly was put down following a severe infection in her near-hind leg.
Guest, 41, of Brancepeth Manor Farm in County Durham, pleaded guilty to failing to exercise reasonable care and supervision.
The HRA will call Guest, plus the stable's head lad Dalton and head girl Tidman, to a hearing on 8 February to consider whether they have breached the Rules of Racing.
If found guilty, a ban of anything from six months to 10 years could potentially be imposed, although other penalties can be given.
The HRA has previously indicated that Guest is more likely to receive a financial punishment after the judge at the court case pointed to mitigating circumstances.