Horsham Plaza Centre manager Allison Roberts said staff and shoppers reported seeing pets trapped inside cars with windows left a few centimetres ajar.

“It causes us great distress because it can become really warm in the cars,” she said.

“Our feelings here are if you don’t think you can leave a child in the car, don’t leave a pet in the car.”

Horsham Rural City Council ranger Nick Meagher said it was important for people to remember the outside temperature was nowhere near as hot as the inside of a car.

“It doesn’t take very long for the inside of cars to heat up and for the dogs to die of dehydration,” he said.

Tests have shown temperatures inside cars can top 70 degrees when the outside temperature is 30, and with the mercury expected to reach 44 degrees, any pet left inside a car even for minutes would be at serious risk.

Mr Meagher said he occasionally responded to animals trapped in parked cars but there was usually little that could be done to save them.

“By the time we get there they’re gone,” he said.

Both Mr Meagher and Mrs Roberts said they would refer any offenders directly to police, who have the authority to smash a car window to save an animal.

RSPCA senior inspector Simon Primrose said pet owners faced tough penalties if they were found to have left an animal in a hot car.

“If found guilty of an offence of this type, the accused could face up to two years’ imprisonment, $71,000 in fines and the prospect of receiving a banning order, being a person prohibited from owning or being in charge of an animal for up to 10 years,” Mr Primrose said.

An RSPCA spokesman said the organisation received 209 reports of animals being left in cars in Victoria last summer.