Joseph Valente, of New York, was celebrating his birthday with a slice of his favourite dessert - apple strudel, when he felt something wasn't quite right.
Joseph was tucking into his favourite strudel when he made the discovery
His nephew Neil Gold said the cake appeared to have a line of black mould in it - something that would later turn out to be the dead rodent.
He added: 'We saw it was coming from the bottom. We flipped it over and seemed to be a rat's tail.'
The rodent's outline can be clearly seen in this shot from ABC
The nephew also added that the rat's tail was 'bleeding into the cake.'
The supermarket chain that supplied the strudel has launched an internal investigation into the matter.
A spokesman made this statement: 'King Kullen has had in-store bakeries for over 30 years and there had never been a case of a rodent in one of our store-baked cakes.'
Gross.