Mine don't normally have a problem with pig ears but they rarely get any.
I would fast them for 24 hours and let their systems rest.
Then start to add some pure canned pumpkin, not the filling.
I always tell people when giving your dog something like a raw bone or in your case a pig ear for the first time, start off with just 15-20 minutes of chewing. Although pig ears don't take very long to chew.