Brennan has also been charged in Victoria in the cases against trainers Danny O'Brien and Mark Kavanagh, the father of Sam.
On the first two days of the NSW inquiry, Sam Kavanagh will answer eight charges, while Brennan and Flemington Equine Clinic general manager Aaron Corby will also answer charges. On day three, another 16 charges against Kavanagh will be heard including raceday treatment to Midsummer Sun.
Camilleri, Mitchell Butterfield and Kavanagh's stablehand Michael O'Loughlin all face charges over the raceday drenching of the horse.
Newcastle trainer Darren Smith, the only person so far penalised for cobalt use in NSW, has his second-level appeal against a 15-year disqualification heard on Monday.
Smith lost in front of the Racing NSW Appeal Panel and took his case to the Appeals Tribunal.
- AAP