Overview of Facial Nerve Paresis (Paralysis) in Dogs
Facial nerve paresis (weakness) or paralysis (total dysfunction) is an abnormality of the facial nerve (7th cranial nerve), resulting in improper function or paralysis of the muscles associated with facial expression. These include the muscles of the ears, lips, eyelids and nose.
In many cases the cause of facial nerve paralysis is idiopathic (unknown). The most commonly identified disease process causing facial nerve paralysis is otitis media-interna (inflammation of the inner and middle ear). Less common, but possible, causes of facial nerve paralysis include:
Facial nerve paralysis occurs in both cats and dogs, but is more common in dogs. Breeds at an increased risk for this disorder include the cocker spaniel, Pembroke Welsh corgi, boxer and English setter. It occurs in adult animals, usually greater than five years of age. There is no apparent gender predilection.
Clinical signs may vary, depending on the underlying cause of the facial nerve paralysis. Usually signs are unilateral (involving one side of the face) but they may be bilateral (involving both sides).
What to Watch For
Signs of facial nerve paralysis in Dogs may include:
Diagnosis of Facial Nerve Paralysis in Dogs
Treatment of Facial Nerve Paralysis in Dogs
There is no specific treatment for facial nerve paralysis in dogs. Any underlying disease should be treated. Animals may need to be medicated with eye lubricants to avoid corneal damage. If keratitis (inflammation of the cornea) or corneal ulcers (defects in the cornea) are identified, they must be treated with appropriate ophthalmic antibiotics.
Home Care and Prevention
Application of ophthalmic medications as directed by your veterinarian is important to avoid ocular complications. Follow-up exams with the veterinarian are recommended to evaluate signs of progression or resolution and to maintain close observations of any ocular problems.
For most cases, there is no specific care to reduce the risk of facial nerve paralysis. However, since this is often associated with middle and inner ear disease, it is important to maintain good ear care, especially in animals predisposed to ear disease such as cocker spaniels. This includes careful ear cleaning and immediate veterinary treatment of all ear infections.
In-depth Information on Canine Facial Nerve Paralysis
Idiopathic (unknown cause) facial nerve paralysis is the most common form of the disease in dogs. A large study of dogs with clinical signs consistent with facial nerve paralysis demonstrated an unidentifiable cause of disease in 75 percent of the cases. In idiopathic cases the signs are usually unilateral and there are no other abnormal physical exam or neurologic findings.
In dogs with concurrent otitis media/interna, there may be a history of chronic ear infections or physical evidence of disease associated with the external ear. However, they may not show obvious evidence of ear disease on physical exam, as inflammation confined to the middle and/or inner ear cannot be seen externally.
Evidence of middle and inner ear disease may be demonstrated by additional neurologic deficits seen as abnormalities of the vestibular system (part of the neurologic system that controls balance). These signs might include a head tilt, nystagmus, strabismus (abnormal eye position), and general lack of coordination. Occurrence of facial nerve paralysis and vestibular abnormalities is strongly suggestive of concurrent ear disease, or brain disease affecting the 7th and 8th cranial nerves at their points of origin in the brainstem.
The impact of facial nerve paralysis on your pet depends on whether or not there is an identifiable underlying cause of disease and what other signs are present. Facial nerve paralysis is a physical exam finding and should not be confused with any other disease process, although there are a number of associated causes that must be ruled out, including:
In-depth Information on Diagnosis
A thorough history and physical exam are imperative in establishing the diagnosis of facial nerve paralysis. The diagnosis itself is made based on the physical exam findings, but as discussed, there are multiple underlying disease processes that must be ruled out. A complete history may provide valuable information that will guide the diagnostic evaluation.
In-depth Information on Treatment
There is no specific treatment for facial nerve paralysis. If an underlying cause can be identified, it is imperative that this be addressed and treated appropriately.
Follow-up Care for Dogs with Facial Nerve Paresis (Paralysis)
Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not rapidly improve. Administer all prescribed medications as directed. Alert your veterinarian if you are having problems treating your dog.
Follow-up exams with your veterinarian are advised to keep track of ocular problems and development of other signs in cases of presumed idiopathic disease, as disease progression may result in the emergence of an underlying cause for the facial nerve paralysis. Additionally, in animals that are being treated for identifiable causes of facial nerve paralysis, response to therapy should be monitored.
Animals with idiopathic disease may recover in three to six weeks, but many animals never recover completely. Most animals tolerate the disorder quite well, as long as the eye is appropriately managed.
Over time, some muscle contracture (shortening) can occur. This may lessen the asymmetry noted in the face, especially in the lips.