The fate of more than 600 Australian-bred greyhounds hangs in the balance with the imminent closure of Macau's infamous Canidrome racetrack.

"The big problem is that we still have 650 animals," Albano Martins, the president of animal rights group Anima, told 7.30.

"What will they do with those animals?"

Hundreds of dogs left in limbo

The Canidrome was notorious for its inhumane treatment of greyhounds. ( Source: Save The Macau Greyhounds )

The Canidrome has been in decline for years.

According to Andrew Scott, the chief executive officer of Inside Asian Gaming, young people aren't as interested in greyhound racing and are more concerned about animal welfare than their predecessors.

"The way the Macau Canidrome was run was perhaps — let's be polite and say didn't have the checks and balances," he told 7.30.

"The respect for the animals wasn't what it should have been. And a lot of young people were not happy about that."

It was that lack of checks and balances that prompted Greyhounds Australasia to stop issuing passports for dogs to be sent to Macau in 2014.

But in 2015, 7.30 revealed that some Australian breeders were flouting the ban and dogs were still being sent to Macau and being held in appalling conditions at the Canidrome.

After the Australian ban, the Canidrome attempted to get dogs from Ireland but that failed and now the track will close down on July 21.

While welcoming the end of the Canidrome, animal rights groups are now concerned about what will happen to the hundreds of greyhounds left without a home.

Anima has gathered adoption forms from more than 600 people around the world who are prepared to rehome the greyhounds but the Canidrome has refused to hand the dogs over to the animal rights organisation.

Despite numerous attempts by Greyhounds Australasia to help facilitate adoptions back in Australia, the Canidrome has not been willing to confirm the greyhounds' identities nor provide access for greyhound behaviour experts to assess the greyhounds' suitability for rehoming.

Instead the infamous racing centre is holding their own adoption days, where members of the public can adopt one of a limited number of greyhounds.

But the small number of greyhounds being adopted raises questions about the hundreds of other dogs that Canidrome staff are not making available.

The Canidrome didn't respond to formal questions, but one staff member did comment.

"We will continue to look after the rest of the dogs, and we will organise a place to keep them," Chris Kuong Weng Hong of the Canidrome Employees' Association told 7.30.

Fears dogs being sent to illegal racetracks in China

Greyhounds from the Canidrome could end up at illegal races in China. ( Source: Save The Macau Greyhounds )

Activists are not buying it.

"They're only giving away the sick animals, the ones in bad shape," Mr Martins said.

"The new ones in good shape, they want to use them on another track, this is our opinion, in mainland China."

While greyhound racing is outlawed in mainland China, illegal and unregulated meets still occur.

Activists believe that these events have been happening for several years.

But local activist, Edith Lam, is worried about more than illegal racing.

"We are very worried they will send dogs to mainland China, because there are so many illegal tracks, and China illegally has a dog meat trade," Ms Lam told 7.30.

She has already adopted a greyhound from the Canidrome and is keeping a close eye on where other adopted greyhounds end up.

'Greyhounds are a beautiful, beautiful dog'

Nora Dieppe is hoping to bring the brother of her dog Millie to Australia from Macau. ( ABC News: Amy Dondalson )

Ms Lam is now also helping return some greyhounds to Australia.

She's contacted Australian greyhound owner, Nora Dieppe, after she discovered Nora's dog Millie had a brother that was racing at the Canidrome.

"I was made aware that [Millie's] brother Jack was racing in Macau," Ms Dieppe said.

"That's when my heart sank."

Through a social media campaign called Bring Jack Home, Ms Dieppe was contacted by Ms Lam, who promised to help return Jack to Australia.

"Recently she gave me a phone call and just said that she's got him," Ms Dieppe said.

"I just didn't expect him to be alive."

Ms Lam and Ms Dieppe are now working together to return Jack to Australia, a process which requires mandatory health tests and vaccinations.

While it costs thousands of dollars and has a six-month waiting period, Ms Dieppe said it was worth the wait.

"They are so enduring, patient, loyal and just kooky," she said.

She is now encouraging other Australians to adopt the greyhounds back to Australia.