These songs in the DT mention ferrets:

I'VE GOT A FERRET by John Cleese.
"I've got a ferret sticking up my nose."

THE FURZE FIELD
"And if you'll come a-ferreting when ferreting's in season..."

THE KING OF BALLYHOOLEY
"I have a house behind yon hill two fine greyhounds and a ferret"

CHARACTER OF A MISTRESS
"Yet in her cunny burrow may two tumblers and a ferret play"