The mailing campaign features statistics that have appeared in newspapers about the number of cats that are abandoned by their owners over the Christmas period, and is part of the charity's wider online and DRTV fundraising strategy.
TDA said the mailing campaign was devised to get a response from people who would not normally donate at Christmas, and was a move away from the typical "cute cat images" to offer a more pragmatic message.
Cats Protection, which provides veterinary care and shelter for lost and abandoned cats, added that according to its latest research, 78% of its supporters felt people did not consider the long-term affects when they chose to get a pet.
Janet Wickens, head of fundraising and communications at Cats Protection, said: "The fact that we had around 7,000 cats in our care last Christmas supports [our research] and suggests that too many people see cats as a disposable item."