Group One-winning trainer Robert Smerdon and one of his employees are facing serious conduct charges relating to race day treatments of more than 100 horses over seven years.

Racing Victoria on Tuesday charged eight people, including other Group One-winning trainers Stuart Webb and Tony Vasil and trainers Liam Birchley and Trent Pennuto after a lengthy investigation sparked by the scratching of Lovani at Flemington in October.

Smerdon and the seven others have been charged with dishonest, corrupt or fraudulent, improper or dishonourable action or practice with stewards saying that on 115 occasions between 2010 and 2017, the trainer was a party to the administration of alkalinising agents and/or medications to a horse or horses on a race day.

Greg Nelligan, who works for Smerdon at Caulfield and is a former employee of Vasil, has been charged with administering or being a party to the administration of alkalinising agents to horses on race day on 123 occasions from June 26, 2010 to October 7 2017.

The investigation began with the scratching of the Smerdon-trained Lovani at Flemington on October 7 with stewards alleging Nelligan administered or attempted to administer an alkalinising agent to the mare before she was due to race.

Trainer Stuart Webb, who is also an assistant to Smerdon, has been charged under the same conduct rule relating to incidents on August 15, 2010, December 26, 2010 and April 28, 2017.

Stewards allege Vasil was a party to the race day treatment of horses on seven occasions between December 26, 2010 and June 7, 2013 while Queensland trainer Birchley's charges relate to November 3, 2011, November 6 2012 and November 3, 2015.

Pennuto, who is currently disqualified over an attempted raceday treatment, Denise Nelligan and Daniel Garland, both Smerdon stable employees, have also been charged.