The RSPCA says it is still receiving daily calls about dogs being left in cars on hot days despite warnings they can die within six minutes from the heat.

"Since January 1 we have had an average of four calls a day about animals that have been left in hot cars," Amanda Swift, chief inspector with the RSPCA in Western Australia, told 720 ABC Perth.

Perth has recorded temperatures over 40 degrees Celsius on two days this week.

On one of these days police attended to a call in Subiaco where a dog had been left for half an hour.

Police and rangers were preparing to smash a window to free the dog when the owner returned, who said he thought the dog would be alright as it had water and the car was parked in the shade.

Same 'stupid' excuses

Ms Swift said it was an unfortunate but unsurprising story.

"The majority [of calls] have been to places where you can't even take animals — shopping centres, hospitals — where people know full well they are not going to be able to take their animal in when they get there.

"The stupidity never ceases to amaze me.

"Members of the public get really upset by it and they ring us and police and rangers trying to get help for the animal."

First aid for heat stroke Remove dog from heat immediately, preferably into an air-conditioned building or, at the very least, into the shade

Remove dog from heat immediately, preferably into an air-conditioned building or, at the very least, into the shade Wetting down the area around your dog can also help to lower the ambient temperature

Wetting down the area around your dog can also help to lower the ambient temperature Lower its temperature by wetting with cool but not chilled water and setting up a circulating fan

Lower its temperature by wetting with cool but not chilled water and setting up a circulating fan Check rectal temperature every five minutes using a digital thermometer and continue cooling process until temperature drops to around 39 degrees

Check rectal temperature every five minutes using a digital thermometer and continue cooling process until temperature drops to around 39 degrees Caution: Cooling too quickly can cause complications Source: RSPCA

Despite a campaign calling on owners to pledge never to leave their dog in a car, RSPCA staff continue to hear the same excuses every time they attend an incident.

"I've never had an issue before; it gets stressed if I leave it at home; I've only been 10 minutes; I've left water and I've left the windows down," Ms Swift said.

"All the time, same excuses.

"It doesn't matter how many times we say your animal will die if you continue to do this, people continue to do it."

After-effects of heat stroke

Although most dogs left in cars do not die immediately, the health effects of heat stroke should not be underestimated by owners.

"A dog in car — they start to cook from the inside out," Ms Swift said.

"It's almost like putting them in a microwave.

"The owners will come back and the dog seems fine, but the heat stress can cause all sorts of problems like blood clotting.

"They could actually die hours or days later without showing any symptoms."

Leave them at home

Ms Swift said the best thing to do on hot days was simply to leave pets at home with access to water and shade.

"Just don't take them out. We get enough warnings when there is going to be a hot day.

"Go about your daily business and your animals will be safe and happy when you get home."

Leaving a dog in a car can constitute animal cruelty and offenders can face fines or go to jail.