Dognappers are using coloured elastic bands as secret markings to target homes with pedigrees inside, animal wardens have warned.
The thieves are reportedly tagging the gateposts and wheelie bins of properties where popular breeds are believed to live.
The Public Protection Partnership (PPP) who deal with animal welfare issues in Bracknell Forest, Wokingham Borough and West Berkshire, have warned residents to stay vigilant.
The markings have been found on a number of homes in South Oxfordshire already, reports the Reading Chronicle.
It comes after reports of a special UV paint found on properties in Leicester, thought to be used for a similar purpose.
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Police found the paint, which looks faint in daylight but glows in the dark, daubed on a number of houses.
Officers said the marking seemed to be made by criminals identifying potential targets after a dog was stolen in nearby Hallaton.
The PPP said: "We have recently been made aware that a number of properties in the South Oxfordshire area have seemingly been marked.
"Clearly this is of concern to all dog owners, and we ask that that you all remain vigilant and where possible to report this either online via the Thames Valley Police website or on the 101 number.
"We would further advise that if your dog stays in the house, then move its location to a harder to reach area and less visible to the outside.
"Lastly, do not post anything on social media with respect to your dog, or any potential litters."
Dog owners have been advised to change their walking routine by walking at different times of the day and make sure their pet is on a short lead.
