Shane Polson, 44, was also convicted of intimidating a senior investigator and failing to provide veterinary treatment to a total of three former race dogs he owned.

Details of Polson's crimes came to light at a court hearing on Tuesday and can now be published for the first time.

In July 2018 Neil Parsons, who was then a Greyhound Racing NSW investigator, saw a malnourished greyhound at Polson's residence.

After the Greyhound Welfare and Integrity Commission was notified, Parsons received a phone call from Polson who said a dead body would be found in Dubbo if Parsons returned to the Minore Road property.

At the request of the industry regulator, police went to Polson's property and found a female greyhound barely breathing.

A Dubbo Regional Council ranger took the greyhound to a vet clinic but upon arrival, she was found dead in the back of the ranger's vehicle.

Police said when they interviewed Polson in September 2018 he revealed he was previously convicted of animal cruelty offences in Victoria.

According to police, Polson claimed the dead greyhound (pictured below) ate some chocolate and had diarrhoea.

When asked if he had sought vet assistance, police said Polson told them he was equipped to deal with the problems despite the fact he had no relevant qualifications.

The greyhound had access to water and food, Polson told police who also accused him of claiming the animal would have survived in his care because the chocolate would have left her system and she could have started eating normally again.

In a statement to police, Dr Ross Pedrana said the dead greyhound weighed 10.5 kilograms when he examined her and did not appear to have ingested chocolate.

"Due to to the state of the body presented to me, which was extremely emaciated and dehydrated, this would not appear to have been consistent with ingestion of chocolate," the vet said.

In court Polson's ex-partner Cara Thompson burst into tears after she divulged details of multiple greyhound deaths.

The court heard multiple greyhounds, including the one that died in July, were obtained from a woman in Singleton in early 2018 because Polson wanted to return to training and racing greyhounds.

Between then and when police discovered the dying greyhound, Ms Thompson claimed Polson changed his mind about what he wanted to do with the animals.

"Because of everything that was going on in Victoria he didn't want anything more to do with greyhounds," Ms Thompson said in court.

"He just wanted them gone pretty much ... gradually, Shane wanted to stop feeding them and they went downhill as well and got into the same condition.

"When they passed away they were wrapped in garbage bags and placed into the bin for rubbish collection."

Ms Thompson, who is no longer in a relationship with Polson, was asked in court why she never told police about his crimes in 2018. She said she was afraid of him.

"I was under Shane's instructions not to talk to the police ... I felt like I didn't have a choice because I was scared of Shane," Ms Thompson told the court.

Magistrate Theresa Hamilton concluded there was "evidence...which is capable of supporting a lot of what Ms Thompson says".

"She admitted that what was done was wrong... she was quite open," magistrate Hamilton said.

"It's clear ... that dog had been starved and neglected for some time and was in a very bad state which would have been evident to any person seeing that dog," the magistrate said.

"Although the manner of death is not clear in relation to the others dogs, I think it is clear ... the dogs all died one way or another because they were not taken to the vet when they should have been."

Polson, who pleaded not guilty to all charges he was convicted of, is expected to be sentenced on January 14.