Sarah Ferguson said her daughter was devoted to Max, a Norfolk terrier
The Duchess of York has issued an appeal for help in tracing her daughter Princess Beatrice's missing dog.
Max, a cream and sand-coloured Norfolk terrier, was last seen on Wednesday afternoon chasing a squirrel into Windsor Great Park, in Berkshire.
In an interview with the BBC Radio Berkshire, Sarah Ferguson said her eldest daughter was "devoted" to him.
She added that an undisclosed reward was being offered for his safe return, "no questions asked".
"He's the devoted and beloved dog of my daughter Beatrice," said Sarah Ferguson.
"We believe he's been picked up by somebody who does not know what to do with him, but if they could take him to a vet or the police station.
"There's a substantial reward offered and it's very important that no questions will be asked."
The duchess said Max went everywhere with her Beatrice, 20, who had been devoted to him for the past seven years.
She described Max as very friendly with "a bit of a tummy" and two missing front teeth.
The duchess added: "Beatrice is distraught without him and we just hope someone can come forward with some information.
"I as a mother would be even more grateful so Beatrice can have a happy Christmas."