On each side the facial nerve passes near to the ear and around the angle of the jaw (around the mandible) . It carries nerve messages to and from the ear, facial muscles, eyelids, the salivary glands (which produce saliva in the mouth) and lachrymal glands (which produce tears).
The facial nerve carries mixed nerve fibres including :
Hypothyroidism, which can cause facial paralysis, is reported to be particularly prevalent in the following breeds of dog : Akita, Boxer, Cocker Spaniel (American), Collie, Doberman Pinscher, English Setter, German Shepherd Dog, Golden Retriever, Irish Setter, Labrador Retriever, Old English Sheepdog, Shetland Sheepdog. However, autoimmune thyroiditis - one of the most common causes of hypothyroidism is now thought to be an inherited problem in about 50 breeds !
Lyme Disease - is a transmitted by deer ticks, and so it is most common in working field dogs and dogs exercised in countryside frequented by deer.
The signs of facial nerve paralysis are predictable from a knowledge of the type of nerve fibre it consists of, and the anatomical areas it serves. Paralysis usually only occurs on one side of the face resulting in :
If the facial paralysis is secondary to another disease, signs of that disease might also be present in the same patient eg hypothyroidism, Lyme Disease, ear infection.
Diagnostic tests may be needed to confirm the diagnosis of other diseases such as hypothyroidism or Lyme Disease.
Blunt trauma usually causes only temporary paralysis and if the underlying cause is known and treatable eg Lyme Disease, ear infection or hypothyroidism - the patient can be expected to recover in most cases.
Long term problems
Updated January 2016