Fido's ass

Does anyone know the phrase "wrinkled as Fidog's ass"?

Fido is a stereotypical name for a dog. Fido's a** just means "a dog's backside".
There are no Google hits for "wrinkled as Fido's ass" though there are about 1200 for just "Fido's ass" which the first couple of pages of hits seem to think Fido's a** is something that looks, smells or tastes bad not something wrinkly..