The campaign, created by Whitewater, RSPCA's direct marketing agency, is sending out a mailing to 500,000 of its supporters to ask for cash donations.
The mailing explains how RSPCA volunteers, charity inspectors and other staff will be working throughout the Christmas period caring for thousands of abandoned and abused animals.
As well as a cash donation, the letter asks supporters to send their own message of encouragement to staff and volunteers working over Christmas by signing and returning a Christmas card that is included with the mailer.
Brendon Elliot, donor development manager at the RSPCA, said: "Christmas and the New Year are always a very busy time for the RSPCA and hundreds of dedicated staff and volunteers give up time with family and friends to ensure that we can be there for all of the animals who need our care."
The campaign follows on from the RSPCA's campaign in October, also created by Whitewater, to develop a range of gifts to help animals in need -- for example, the Pamper Hamper dog care kit and Prickly Disposition care for hedgehogs.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .