Police are appealing for information after the offence at Riggs Head, Irton Moor Lane.
It was as reported yesterday, but is believed to have taken place on July 26.
North Yorkshire Police said the gate to the lamb's field was left open by the culprits and the lambs were allowed free, and it is believed 25 of them were subsequently stolen.
A force spokesperson said: "The lambs had recently been dipped and it is possible that their meat could cause illness if consumed.
"Officers are currently awaiting the results of tests to determine the level of risk.
"In the meantime they are advising members of the public to be cautious of any lamb offered for sale under dubious circumstances and to contact the police if they have been offered any cheap lamb meat for sale.
"They are also appealing to anyone who has any information about suspicious people or vehicles seen in the area at the time or, if they are aware of anyone has tried to sell cheap lamb meat in the Scarborough area since the theft."
Anyone with information is asked to contact North Yorkshire Police on 101 or email [email protected]
Quote the North Yorkshire Police reference number 12180147407.