RSPCA made the plea after its Birmingham Animal Hospital and Centre received five calls from distressed people within 24 hours.
They had received a scam call from someone falsely claiming to be from the charity – with a demand for £200 for life-saving surgery.
A spokesman from the RSPCA said: “A member of the public has been contacted by someone claiming to be an RSPCA officer. They’ve been told that their missing pet is at Newbrook Farm [where the centre is based] or at a local vets and they must pay £200 for life-saving surgery or their pet will be euthanised, or are asking for a fee in order for the pet to be returned.
“The fraudsters are mirroring our phone number so the incoming call displays 0300 123 8585 which is particularly concerning. We believe that these people are scouring websites and social media to find missing pet posters and are targeting those owners who have offered financial rewards.
“It’s disgraceful that these scammers are preying on already distressed pet owners and we’re incredibly concerned that they may end up pocketing hundreds of pounds from owners who are desperately looking for their missing cats.”
The charity doesn’t ask for money for veterinary care for missing pets over the phone, with people who receive a call like this urged to not give out their personal details.
Anyone who is contacted about a missing pet in RSPCA’s care should ask for a reference number, the officer’s name, and then call their national call centre on 0300 1234 999 (between 7am and 10pm).
The spokesman added: “We’ve been contacted by five individuals who, thankfully, did not fall foul of the scam and contacted us to find out if we did in fact have their pet,” the spokesperson added.
“If your pet is missing please alert your microchip company and inform local rescue centres and vet practices as well as speaking to neighbours and local businesses.
“If you are using missing pet posters or sharing your pet’s details online please be aware that your phone number may be used by scammers and be incredibly careful when offering reward money or sharing any banking details over the phone.”