Facial Paralysis and Paresis in Dogs

What is facial paralysis and paresis?

Facial paralysis occurs when the facial nerve stops working, causing a complete loss of movement in the affected facial muscles. The facial nerve is responsible for facial expression, eyelid blinking, and tear production. Facial paresis occurs when the nerve only partially loses function, causing facial muscle weakness. Both conditions can reduce or prevent blinking and tear production.

What causes facial paralysis?

In most cases, facial paralysis is considered idiopathic, which means the cause is unknown. Bell’s palsy is a similar condition that occurs in people.

Anything that causes damage or swelling around the facial nerve or the area of the brain the facial nerve comes from can result in paralysis. Since this nerve passes close to the inner ear, any inflammation or infection of the inner or middle ear (otitis interna or otitis media) can result in facial paresis or paralysis. Less common causes include injury, hypothyroidism, generalized nerve disease (polyneuropathy), immune-mediated disease, surgery, and in rare cases, cancer.

Are certain dogs more likely to develop facial paralysis?

No inherited or genetic cause has been identified, but Cocker Spaniels and Cavalier King Charles Spaniels appear predisposed to idiopathic facial paralysis. This condition is most often seen in dogs older than five years of age.

What are the clinical signs of facial paralysis?

Clinical signs of facial paralysis appear suddenly. Dogs with facial paralysis cannot close their eyelids or blink, or they cannot move their ears or lips. Their lips and ears may appear to droop. This paralysis may occur on one side (unilateral) or both sides (bilateral).

Facial paralysis can reduce tear production and affect a dog’s ability to blink, so you may see thick, gray discharge in or around the eyes. They may also have difficulty eating and drool excessively.

How is facial paralysis diagnosed?

Your veterinarian may suspect idiopathic facial paralysis based on your dog’s history and physical examination. Your veterinarian may perform a Schirmer tear test to check your dog’s tear production. Blood and urine tests may be recommended to look for other disease.

In all cases, especially if your dog has a history of otitis externa or ear infections, your veterinarian will need to perform a thorough exam of your dog’s ear to check for evidence of otitis media or interna. This assessment may require sedation or anesthesia. Advanced imaging such as CT or MRI is often required to definitively diagnose these conditions.

How is facial paralysis treated?

There is no specific treatment for idiopathic facial paralysis, although acupuncture may speed recovery time. If your dog has reduced tear production (keratoconjunctivitis sicca or KCS), they will need frequent eye drops (including lubricants) and your veterinarian may recommend a tear stimulant called pilocarpine. KCS can cause corneal ulceration, which requires additional treatment. Your dog will also benefit from regular cleaning around their mouth to prevent skin sores.

What is the prognosis?

Some dogs recover on their own within weeks to months, but some dogs only recover partially, and others do not recover at all. Dogs can have a good quality of life despite facial paralysis if secondary conditions like KCS are well managed. Monitor closely for signs of ulceration such as excessive tearing and redness. If facial paralysis is chronic, the muscles on the affected side of the face may tighten, causing your dog’s face to return to its normal appearance.