Tales, does yours have canvas lining as well? I thought it looked to be from your pictures, but maybe that was a printed paper.
I have a deodorizer powder for my carpets due to an aged, leaky dog......as a last resort I may also try that. The odor isn't overpowering, in fact from the outside it just has that old, familiar farmhouse smell I remember from the family home. Sunshine and fresh air may make a world of difference.