I'm dealing with this!!!!! I believe it is termed Trigeminal Neuritis. It is similar to Bell's palsy in humans. Can be caused by rabies, auto immune or just a random hit of it. Asti my Australian got hit with it last Monday. Not a darn thing can be done but ride it out. All her labs can back perfect so hers is random.
It's so sad!!!! She can't close her mouth. She is drooling horrendously!!! She is eating, but its difficult. Her tongue works and she can swallow. Getting food into her mouth is hard. The worst part is she is horribly depressed!!!!
I hope it goes away soon!