A greyhound trainer and her husband have been arrested in connection with the "mass murder" of 55 greyhounds in Queensland.

The bodies of the dogs were found dumped in Coonarr, near Bundaberg, on 31 March, among 22 spent bullet cartridges. The RSPCA said the deaths were being linked to greyhound racing.

Police have now charged a 64-year-old woman and a 71-year-old man, both from Bundaberg, with the unlawful possession of a firearm after officers raided an address in the Queensland city.

The RSPCA believed the dogs, which were found in various states of decomposition, were killed before ABC's Four Corners was due to expose further shocking revelations behind the greyhound racing industry. Earlier in 2015, the TV channel caused outrage after it showed dogs chasing and mauling other animals.

"The indications are that these may just be young dogs that didn't have the speed, basically. But that's really all we know," RSPCA spokesman Michael Beatty told Fairfax media.

"Unfortunately as I think most people would be aware, there's always been a lot of wastage in the greyhound industry."

Jo-Ann Miller, Australia's Minister for Police, condemned the "mass murder" of the dogs. She said: "The people who have perpetrated this crime to me are oxygen thieves, they are cowards, and they are pathetic."

Detective Inspector Mark Ainsworth said the discovery was "nothing short of abhorrent". The pair are due to appear at Bundaberg Magistrates' Court on 3 March.