Large numbers of animals are euthanased each year in pounds run by the RSPCA, local councils and other groups yet the exact figures - and the reasons they end up being killed - are hotly disputed.
Many animal campaigners say the heart of the problem lies in the oversupply of dogs and cats.
They contend that too many animals are bred for sale through pet shops to owners who are ill-equipped to care for them. These animals, they say, are often abandoned or surrendered in many cases to be euthanased.
Pet shop owners and the Australian Veterinary Association say there is no evidence the shops are to blame. In a recent edition of industry bulletin Pet Industry News welfare groups were accused of trying to "destroy retail pet shops".
The pet industry is also implacably opposed to a bill sponsored by Clover Moore that would ban dog and cat sales in pet shops and which may be reintroduced this year.
And now the campaigners have called the industry's bluff by asking for a broad-ranging public inquiry in the NSW upper house and directing hundreds of letters to MPs and ministers from supporters.
They have also won the backing of Greens MLC Ian Cohen, chairman of the committee best fitted to conduct the inquiry.
"All those statistics that we talk about - even the ones that come from some welfare organisations - are untested and unfounded," said Derek Knox founder of a group called Cat Rescue.
"The first goal for the inquiry is to get real, hard actual data for us to all make business decisions around. We want to come out with a proposed complete method of reforming the whole problem - not just pets in pet shops or backyard breeders but the whole problem."
But Joanne Sillince, chief executive of the Pet Industry Association of Australia was scathing about the need for an inquiry, saying an expert review of the evidence, similar to one recently conducted by the Queensland Government, would be enough.
"I actually don't think an inquiry is going to achieve anything that couldn't be achieved more cost efficiently by other means," she said.
"If it's a choice between spending upwards of a quarter of a million dollars on a parliamentary inquiry or appointing an eminently qualified expert ... we would support the more cost-efficient alternative."
However, Mr Knox said the cost of an inquiry could easily be met from the registration fees collected from pet owners each year and anything less than a full public inquiry would "end up being a marketing exercise for the pet industry".
Mr Cohen said he supported the inquiry and was still seeking the support from a majority of committee members to set it up.
"I think there are some pretty important issues that revolve around irresponsible pet ownership and issues within the industry that facilitate that," he said.