Facial paralysis in cats may result from injuries caused by rough handling or other trauma, such as automobile accidents or ear infection. Paralysis on one side of the face is common when the facial nerve is damaged. Facial paralysis on both sides of the face can be more difficult to recognize, but affected animals often drool and have a dull facial expression. In total facial paralysis, the animal cannot move its eyelids, ears, lips, or nostrils. In partial paralysis, the muscles of facial expression move less than normal.
The signs of facial paralysis vary with the location and severity of the injury. One or both sides of the face can be affected. Usually, the signs include loss of motor function, including the inability to blink, a drooping ear, a drooping upper lip, and drooling from the corner of the mouth. When the animal eats or drinks, food and water may fall out of the mouth. Tear and saliva production may also be reduced, resulting in a dry eye and mouth. Depending on the cause and location of the damage, other neurologic signs (such as incoordination, weakness in 2 or 4 legs, or head tilt) may be seen.
Infection of the middle ear is another common cause of facial paralysis; this can be diagnosed with skull x-rays, magnetic resonance imaging (MRI), or computed tomography (CT) scans. The prognosis for recovery can be good if the diagnosis is made early and the animal receives appropriate antibiotic treatment. However, the facial nerve paralysis can be permanent, and longterm administration of eye drops may be necessary.
Cats can also develop tumors that affect the middle ear and facial nerve. Your veterinarian can diagnose these tumors by looking at the area with an otoscope and taking a sample of abnormal tissue. Computed tomography (CT scan) and magnetic resonance imaging (MRI) may also be necessary for diagnosis and to plan surgical removal. If performed early on, surgery and radiation may result in a good longterm outlook for some types of tumors.
Idiopathic facial paralysis (like Bell’s palsy in humans) is diagnosed in the absence of infection, injury, tumor, or trauma. Domestic long-haired cats are at increased risk. There is no treatment, and regular administration of lubricating eye drops may be necessary. One or both sides of the face can be affected, and the condition can be either temporary or permanent. It can occur on one side, disappear, and then occur on the other side at a later time.
Electromyography, including electrical stimulation of the facial nerve, can be used to determine the location and severity of the injury. There is no specific therapy for injury except electroacupuncture, laser therapy, massage, and heat applied to the affected muscles. Some animals may also need special water containers and soft food. The facial nerve can slowly regenerate, so repeated neurologic examinations can help determine if an animal is recovering. If there has been no improvement after 6 months, the chance of recovery is poor.