droopy lip on my GSD

Question
I have a GSD who is almost 10 yrs old.  She went to the vet for a thorough check up about 7 mths ago and everything came out wonderful!  About 3 weeks ago, I noticed that her bottom lip on the left side is hanging.  I can see her molars and drool comes out.  There is no other signs of drooping in her face at all and she is acting normal.  She is an inside dog and only goes outside with me when she is on a leash or in my site, so I know she didnt injure herself.  What could this be?
Thank YOu,
Sherry

Answer
Most likely the facial nerve is not functioning properly.  In true cases of what we call HORNER'S Syndrome, the eye lid on that same side usually droops and often the pupil may be a different size than the other eye. This can stem from an inner ear infection or chronic ear infections.  In people, the term Bels Palsy is used when there is damage or inflammation of the facial nerve.  This actually occurred in our one dog from Lyme Disease.  I would recommend taking her to the vet for an exam.