Harness racing identity John Camilleri has named vet Dr Adam Matthews as the person who put him in touch with trainer Sam Kavanagh to drench his horses.

Matthews has also been named as the source of a substance containing high levels of cobalt which fellow vet Tom Brennan supplied to Kavanagh as a vitamin drip.

Camilleri appeared as a reluctant witness on the first day of the appeals by Kavanagh, Matthews, Brennan and Aaron Corby who have all been disqualified for their roles in the cobalt case against the trainer.

Mitch Butterfield, the man who drenched Midsummer Sun, and Camilleri are also disqualified but have not appealed.

Camilleri said he believed the drenches were to be administered post-race, something he did not say at his own hearing last year.

"I was under pressure. My name was in the papers and I couldn't handle it," Camilleri said.

"I just told then what they wanted to know so I could get out of here."

He also denied knowing anything about cobalt but records of a text message exchange between Camilleri and Harness Racing NSW integrity head Reid Sanders on January 14, 2015, revealed the names of several trainers who had been investigated.

At the time Camilleri was put in contact with Sam Kavanagh, he said Matthews told him the trainer was desperate to get winners because he was tired of running second.

Kavanagh was the only other person to give evidence on Monday, saying Brennan had supplied the Vitamin Complex which he believed was also being used by his trainer father Mark and Danny O'Brien, both of whom are appealing cobalt bans in Victoria.

"It was coming from the same place. I thought it was vitamins and they were training winners so I thought I would use it too," Kavanagh said.

"But when they returned positives to cobalt I worried that's where it had come from.

"With us having the same vet, naturally I thought that could be the cause."

Kavanagh said Corby, the office manager at the Flemington Equine Clinic, had told him to get a second phone and throw out his computer.

Kavanagh will be cross examined on Tuesday.