More than 1,200 pets have been starved of food and water since October in Queensland, with the RSPCA pleading with owners to take more responsibility in sweltering heat.
RSPCA spokesman Michael Beatty said a spike in cases was not due to owners being deliberately negligent, but instead a lack of awareness of how dangerous hot temperatures could be.
"We've had a number of animals that have died from heat stress in the backyard and a couple of those were directly due to dogs being tethered and getting their tether caught," Mr Beatty said.
"Then they can't get back to the shade and they can't reach the water.
"A dog can survive more than a few days without food, but without shade and without water in this heat they will die."
Mr Beatty said the RSPCA had recorded 386 cases of animals being left in cars and 742 reports of pets without proper shelter in the past three months.
He said temperatures inside cars could shoot past 50 degrees Celsius within minutes, leaving older dogs or vulnerable breeds less than a 10-minute survival window.
"It defies belief to be honest that someone could leave their animals in a car with the heat we're getting, not just in Queensland of course but all over Australia," he said.
Mr Beatty said it was best to leave pets at home if possible, provide proper ventilation if kept inside and give them access to multiple water bowls.
Bureau of Meteorology figures show minimum temperatures higher than average across the country in October, and in the following month days and nights were warmer than usual in north Queensland.
In December, the average maximum daily temperatures in Brisbane was 30 degrees Celsius, with a similar trend continuing during the first week of January.
