Has your dog suddenly developed a lopsided smile? Facial paralysis in dogs is a condition that is characterized by changes in your dog's expression and facial control. If your dog is looking like a canine Harvey Dent, don't worry. Most cases have a favorable outcome even if some dogs require extra care following their diagnosis. Read on to learn about the causes and management of this condition.
Causes of Facial Paralysis
Facial paralysis results from damage to a facial nerve called cranial nerve VII. This nerve is connected to the muscles that control your dog's eyelids, lips, nose, ears and cheeks, and when it's damaged a portion of his face can appear frozen or droopy. The effects of nerve damage may persist for an extended or indefinite period of time.
Cocker spaniels, beagles, corgis and boxers are more frequently affected during their mature years compared to other breeds. Depending on the underlying cause, temporary facial paralysis in dogs can last several weeks. Possible causes of facial paralysis include:
- Middle and inner ear infections
- Trauma to the head
- Endocrine disorders (hypothyroidism, diabetes mellitus, Cushing's disease)
- Toxins, including botulism, which is used to synthesize Botox and which dogs can get from eating raw meat, according to Wag!
- Tumors, especially growths that invade or compress cranial nerve VII or the brainstem
Surprisingly, the majority of cases of facial paralysis in dogs are idiopathic and not traceable to a specific cause. A slim margin can also be iatrogenic, or accidentally caused during surgery.
Depending on the underlying cause, the signs of facial paralysis in dogs can manifest on one or both sides of the face. Pet parents familiar with Bell's Palsy, a form of facial paralysis in people that the Mayo Clinic notes also includes nerve damage, will notice a similar change in the appearance of their dog's face. The common signs of damage to cranial nerve VII include:
- Drooling (the facial nerve also controls the salivary glands)
- Drooping of the lip and ear
- Deviation of the nose toward the unaffected side
- Inability to blink and close the affected eye
- Sloppy eating, dropping food from mouth
- Eye discharge
If you suspect your dog has facial nerve paralysis, contact your veterinarian. They will perform a comprehensive physical exam of your dog's eyes, ears and motor coordination and check for other cranial nerve and systemic neurological problems.
Looking Out for Dry Eye
An important part of your vet's exam will be testing your dog's ability to blink with the eye on the affected side of his face. Pet Health Network notes that a significant risk of facial nerve paralysis in dogs is keratoconjunctivitis sicca, commonly known as dry eye. This condition develops when a dog can't produce enough tears or close the affected eye.
Your vet may conduct an exam called the Schirmer tear test to see if your dog's eyes are producing enough lubrication. They may prescribe artificial tears since dogs with dry eye are at risk for developing corneal ulcers.
Besides a thorough exam of your dog's eyes, the vet will also closely evaluate his ear canals. From their point of origin in the brain, the fibers of cranial nerve VII run close to the middle ear on their way to the face. An ear canal exam helps rule out an external ear infection, but in order to definitively determine if middle or inner ear or brain disease exists, CT or MRI scans are often needed.
Some cases also impact cranial nerve VIII, the vestibulocochlear nerve, which lies in close proximity to cranial nerve VII. Cranial nerve VIII transmits both sound and information about the body's sense of balance from the ear to the brain. Veterinary Partner notes that a disruption of cranial nerve VIII causes vestibular disease, which manifests as an unsteady gait, weakness, head tilt and nystagmus (abnormal eye movement).
Although the underlying cause of most cases of facial paralysis in dogs remains unknown, your dog's vet might recommend blood work to rule out other conditions. Other tests they might prescribe include a complete blood count, a chemistry profile and a thyroid function profile, which are helpful in evaluating various hormonal disorders associated with facial paralysis.
Idiopathic facial paralysis in dogs does not have a prescribed treatment except for supportive care. An important part of caring for your pup is avoiding the complications related to dry eye and the inability to blink. If your vet prescribes artificial tears to keep the affected cornea lubricated, administering drops several times daily is critical for preventing infection and corneal ulceration. Since you cannot rely on your dog to squint with pain due to a corneal ulcer, pay close attention for any redness around his eye and seek veterinary care if you suspect a problem. Untreated corneal ulcers can be very serious.
In case of an ear infection, your dog will need a course of antibiotics and sometimes surgical intervention. If blood tests reveal an underlying disease or if a tumor is found on imaging tests, you and your vet can discuss ways to manage the underlying problem.
Uncomplicated facial paralysis in dogs is not typically life-threatening. Even dogs who are challenged by facial paralysis and vestibular disease often make a full recovery. Although idiopathic facial paralysis can be aesthetically disconcerting for pet parents, rest assured, it is not a painful condition for your dog. If you notice any problems, contact your vet. Immediate attention will ensure peace of mind and the optimal care for your pup.
Mindy Cohan, VMD
Mindy Cohan is a veterinarian in the Philadelphia area and a graduate of the University of Pennsylvania School of Veterinary Medicine. She has a rescue dog named Jem. Mindy enjoys hiking with Jem while listening to podcasts about the American Civil War and Abraham Lincoln.