Is it possible to pour a lot of baking soda into the duct without it being blown out when the heat comes on? If so, pour some into the duct (providing it's dry now) and leave it overnight at least, then vacuum it out with a shop vac if you have one. It should absorb the odor. Vinegar is a good odor neutralizer as well, but may corrode the metal. Poor Disney girl. We went through that with our RB dog Maggie, and it was the pits.