Thousands of animals could remain living in inhumane conditions as a major cruelty investigator faces a massive staff and funding shortfall.
But a state government warns it does not have an "endless supply" of money for longer-term funding, amid budget constraints.
People have been unable to make online animal cruelty reports to RSPCA NSW after the reporting tool was recently taken offline.
While phone complaints can be made, the online reporting tool's shutdown is being cast as a necessary step as a near-halving of government funding begins to bite.
Resourcing challenges have frustrated people reporting potentially cruel conditions.
People with complaints have told the Coalition for the Protection of Racehorses they are being turned away from the RSPCA.
"We hear from people who have tried to report horses that are in imminent danger and the RSPCA simply refuses to take it on because they're out of capacity," coalition general manager Helle Erhardsen told AAP.
Vera Elcham spent nearly four months lodging a cruelty complaint for a local dog left tied up in the rain and was eventually told the case was closed to prioritise other matters.
"It definitely puts less confidence in the RSPCA because I know everyone in that situation, it's the first organisation you would call," the 51-year-old from Sydney's east told AAP.
Under state law, animal cruelty legislation is almost entirely enforced by the RSPCA.
The RSPCA investigated 17,000 cruelty complaints in 2023/24, including for animals with no food or water, locked in small pens or left alone for more than 24 hours.
It also began 96 prosecutions over the treatment of nearly 2000 animals.
That followed a $20.5 million grant from the outgoing coalition government "to expand enforcement of animal cruelty laws".
The following year, enforcement funding dropped to $11.3 million under the incoming Labor government.
RSPCA NSW said it had asked for recurring funding at the higher level but Labor was "not minded" to commit to that.
Funding needed to be at least indexed to $21 million if the government wanted the charity to respond to up to 18,000 annual complaints, chief executive Steve Coleman said.
"If we can't sustain our own financial endeavours then ... that puts at risk all of the other activities that our organisation deals in, including supporting domestic violence victims and the homeless," Mr Coleman told AAP.
Premier Chris Minns said the RSPCA funding decisions could not be made on longer timelines and the charity had received an "enormous amount" of money.
"But it's not an endless supply of money and we'd have to come to an arrangement with the RSPCA about ongoing funds," he told reporters on Monday.
The $20.5 million grant by the previous government was "money well-spent" for infrastructure, but budget constraints affected ongoing funds, Mr Minns said.
Agriculture Minister Tara Moriarty said the RSPCA had enough funding to perform its duties. The state funding was based on the amount needed for 53 inspectors.
"The government is advised the RSPCA currently has 40 registered," she told AAP.
Animal Justice MP Emma Hurst is worried RSPCA inspectors won't be able to properly police animal cruelty.
"We have passed legislation to protect animals. The community would be horrified to hear that those laws are not being properly enforced," Ms Hurst told AAP.
"Without full enforcement, those laws are worth nothing."
The NSW budget for 2025/26 will be handed down on Tuesday.
