Two-and-a-half-year-old Kya went missing from a garden on Milbourne Street, Blackpool, at around 6.30pm on Tuesday.
Kya was let out into the back garden by her owners but was missing when they went out to check on her and the garden gate was open.
David Smith, 39, said: “We have a really high fence and a big bolt on the gate so she wouldn’t have been able to get out of the garden on her own.
“She’s really timid and hasn’t got a bad bone in her body.
“She’s never been on her own so she will be really scared.
“If anyone knows where Kya might be, please can you help return her to her loving family.
“She means the world to me.”
Terry McCarthy, 30, David’s partner, said: “When we went to get a dog, there were two sisters – Kya and Kes – left, so we decided to get both of them so we didn’t have to separate them.
“Kes is really panicked. I’ve got her wrapped in a blanket to try and keep her calm.”
French bulldogs are an increasingly popular breed in the UK and have become a target for thieves with the dogs changing hands for thousands of pounds.
French bulldogs are most likely to be taken if left unattended in cars, gardens or outside shops, according to breeders.
Two years ago, a Blackpool dog owner was reunited with his stolen pet after turning into an amateur detective to track down the missing mutt.
Gaz Kennedy’s French bulldog puppy Rocco was swiped from his Nethway Avenue home on Saturday night while he and his children slept.
Vowing never to give up on finding his 16-week-old pet, Gaz took matters into his own hands and appealed for help online.
A Facebook post featuring pictures of Rocco was ‘shared’ more than 28,000 times, and soon enough, Gaz says he was contacted by a person who believed they knew where the dog was being held.
Anyone with any information about Kya’s whereabouts can contact David on 07496 673613.