A statement from the police said: "We are aware of reports on social media about a man knocking on doors in the Woodston area reporting to be from the RSPCA.
"The reports say the man claims to be looking for stolen dogs and wants to check the property.
"We have been in touch with the RSPCA who have confirmed [their staff] would be able to provide ID (which will be on show with a lanyard), would be in RSPCA uniform and would not be knocking door-to-door.
"Please be cautious before letting anyone into your home – genuine callers will expect you to be careful and will not mind you asking to see their ID or confirmation of who they say they are.
"If you are unsure, ask them to come back at a time that suits you when someone you trust can be with you."
Genuine callers are unlikely to mind returning at a better time when someone else can be at the property, they said.
Official police advice about bogus callers says that they are often committing a distraction burglary where they can trick their way into homes in order to steal valuables or money.
Further advice about bogus callers can be found on the police website.
Anyone with information about these incidents can report it to the police by using the online webchat or by calling 101.