Cat the Dog first appeared in the Dec Says/The Secret of My Success run of sketches (see below) before starring in her own series of skits upon Ant and Dec's departure. Each episode would begin & end with Cat writing in her diary. Joined by her bestest ever ever friend pop star Louise Redknapp, Cat the Dog was dressed as a goofy Brummie teenager with huge false teeth & big wild hair and spoke with a mock Birmingham accent (it's ever so different from Bir-ming-ham!).

A recurring joke involved Cat mentioning that she had measured herself again and nothing was growing (implying that she was measuring her breasts). Towards the end of the series, she said that they were growing and she would soon be able to fit into a larger shoe size.