Issue Description Facial nerve paralysis is a common problem
that involves the paralysis of any structures innervated by the facial
nerve. The pathway of the facial nerve is long and relatively
convoluted, and so there are a number of causes that may result in
facial nerve paralysis.
Causes In most dogs, facial paralysis is not
associated with disease of the brain, but rather with direct damage to
the nerve that controls the muscles in the face (facial nerve). This
nerve comes from the back of the brain to control the muscles of
facial expression (ears, lips, eyelids and nostril).
The most common cause of facial nerve paralysis in dogs is idiopathic
facial nerve paralysis. The term idiopathic means that there is no
known cause. Therefore in idiopathic disease all the tests results
will be normal. A similar condition is recognised in human medicine as
The second most common cause of facial nerve paralysis is a deep-
seated infection of the ear (otitis media/interna). In this case other
signs such as Horner's syndrome (decreased pupil size and third eyelid
coming across the eye) and/or vestibular syndrome (head tilted to one
side, and balance loss) are frequently seen in addition to facial
paralysis. Rarely, facial paralysis can be associated with disease
affecting multiple nerves (polyneuropathy) or brain disease (tumour,
infection or inflammation). In these cases, other neurological signs
are usually observed in addition to facial paralysis.
Symptoms A dog with facial paralysis has a dropped
appearance to the face on one side. One ear is held lower than the
other and the lip hangs down on the affected side. Affected dogs are
unable to blink and have a tendency to dribble saliva and drop food
from the side of the mouth. Occasionally, the same signs may be
present on both sides of the face which can make the changes difficult
Diagnosis Your vet will first want to perform a thorough
ear examination to detect signs of ear infection. If this examination
is normal then the deeper parts of the ear and brain may be examined
using specialised imaging techniques. The deeper part of the ear can
be seen on X-Rays of the skull and the back of the brain can be
examined using CT or MRI scans. In some cases it may be necessary to
take a sample of fluid from around the brain to check for signs of
Treatment Idiopathic facial nerve paralysis is usually
left untreated because, by definition, no cause has been identified.
Facial nerve paralysis secondary to otitis requires at least 4 to 6
weeks oral antibiotic. Cases that are unresponsive to medical
treatment may require surgical drainage.
Prognosis Although, the signs are often permanent (even
when an underlying cause is identified and adequately treated) this
will rarely have any significant effects on your dog's quality of
life. If there is no underlying cause of the nerve damage the outlook
is good. After a couple of weeks the early signs (dribbling of saliva,
dropping of food and a floppy lip) are replaced by the 'chronic'
signs. The droopy lip will start to contract so that it regains its
normal size and shape - although the animal will remain unable to move
their lip. On rare occasions, the other side of the face may also drop
at a later date.