Pet owners across the UK have been reporting stickers mysteriously appearing on their front door.
The small stickers have been appearing on homes within the Merseyside area, with people fearing it's a signal for thieves to target homes with family pets.
Dog owners have been sharing their concerns across social media groups, urging pet owners across the UK to stay alert.
After finding a blue sticker on her door, one worried dog owner said: "Woke up to this on my door this morning.
"Never had anything like it before. I've obviously posted on the Crimewatch group only for head up to pet owners and to see if anyone has had similar.
"I've had a few sarcastic comments but as I've said I'm not usually one for all this but just find it a bit odd.
"Both my dogs are male, one being worth a lot of money.
"Just wanted to let people know here in case it is something to be concerned about."
As a precautionary measure, the woman has installed CCTV outside her home.
Warning for dog owners before ‘it’s too late’
Another dog owner in Birkenhead reported a similar incident. She said: "I really just wanted to let people know before it's too late. It's disgusting how we have to live.
"Luckily I have a dog who wouldn't let anyone a foot near the door but who's saying he wouldn't get poisoned or something?
"I know it's far fetched but it happens and for what my new pup's worth, it's easy for them. This pup is worth more than everything in my home."
According to the Metropolitan Police, if your dog is stolen you should call the police and check if the council has your missing dog through this GOV.UK link.
Also, contact the microchip database holding your dog's details and update them about the theft.