Archie, a black and white cat, has been missing from his home in Ballingdon Street, Sudbury, since July 14.
Owner Angela Johnstone said the behaviour is completely out of character for the pet, which has a black body with a white neck and paws.
“I just want to know something, it drives you insane not knowing what has happened,” she said.
Mrs Johnstone is offering a reward for information from anyone who knows what has happened to Archie.
Call her on 07803 176833.