Tori Spelling -- My Tiny Dog Has Gone Missing!

Tori Spelling's 6 lb. pup is missing and she's offering a reward for its return.

The former "Beverly Hills, 90210" star posted fliers around her Calabasas neighborhood pleading for information about her long-haired terrier mix named Mitzi.

Tori says the dog is microchipped and has an ID collar, but the contact info is outdated. The situation's even more frantic because Mitzi needs medication.

Tori says she's set up an email address for info about the dog ... mitzimissing@gmail.com.

The Spelling fam doesn't have the best history with dogs -- a pit bull they were boarding nearly bit the dust last year because the bill went unpaid.