Forced to diet for three months, the temptation of unguarded ‘’pupcakes’’ was too much for Charlotte on Saturday.

Staff from the RSPCA shelter in Unanderra could only look on as the little beagle dog scoffed down the tasty treats.

‘’Ah well, it’s all for a good cause,’’ a staff member said, making reference to RSPCA Cupcake Day, which raises funds to fight animal cruelty.

The annual RSPCA Cupcake Day will be held nationally on Monday, August 15, but staff at Unanderra started their fundraising campaign on Saturday and will continue baking and selling cupcakes on Sunday and Monday.

Illawarra RSPCA shelter manager Judith Wright said Saturday was traditionally the Unanderra shelter's big day.

‘’It is getting bigger and bigger every year. It has been wonderful to see how many people bake cupcakes and also donate them to us to sell,’’ Ms Wright said.

‘’This is always one of our most enjoyable fundraisers for the year. It’s a day where everyone can use their baking skills and bake cupcakes, pupcakes, cakes and slices.

‘’We hope to sell about 400 cupcakes over the three days and if we can raise a couple of thousand dollars in the process, that will be fantastic.

‘’All money raised stays here in the Illawarra and will be used for the animals at the shelter here.’’

The $1.5 million raised nationally from the annual event in 2014 helped the more than 130,000 animals that came into RSPCA shelters across the country.

A spokesman from RSPCA NSW said the importance of Cupcake Day could not be overstated.

‘’Without the public's support there would be nowhere for these animals to turn to when they are abandoned, abused or unwanted,’’ he said.

‘’We wouldn't be able to investigate allegations of cruelty and neglect. Money raised by people popping some batter in the oven is vital to animal welfare in this country.’’

Ms Wright said the all-purpose Unanderra shelter at 54 Industrial Road, could accommodate 200 to 250 animals at any one time.

‘’With the size of the shelter and the amount of animals we get in we do need community support to help with the cost of rescuing, treating, rehabilitating and sheltering the animals who come into our care,’’ she said.