Facial Paralysis in Dogs: Symptoms, Causes and Treatment

Written and verified by the biologist Samuel Sanchez

Last update: 27 December, 2022

Facial paralysis in dogs is a more common condition than it seems, especially in older and elderly dogs. This clinical sign manifests itself with an inability to move the facial muscles and keep them tense, not due to muscle failure, but due to disorders that affect the nerves that control them.

Even though this condition is well known, it should be noted that up to 74% of cases in the veterinary clinic are idiopathic in nature, that is, they don’t have a specific cause – or it hasn’t been discovered. If you want to know everything that we know so far about facial paralysis in dogs, read on.

What is facial paralysis in dogs?

The facial nerves are mixed cranial nerves that contain sensory, motor, and parasympathetic fibers. These nerve pairs emerge directly from the brain at the level of the brainstem and are distributed through the holes in the skull through the head, thorax, and abdomen of the animal.

Eye movements, photomotor reflexes, accommodation, the transmission of olfactory impulses, perception of sensory information, taste impulses, and placement in three-dimensional environments are mediated by the facial nerves. If these are damaged, facial paralysis occurs in dogs or any other vertebrate.

Facial paralysis is hardly ever the product of direct damage to the brain, but rather to the facial nerve that connects it to the outside through touch, taste, sight and other perceptions.

Symptoms of facial paralysis in dogs

As indicated by the Davies veterinary portal, the signology of facial paralysis in dogs depends on the severity of the injury and the affected nerve structures. Normally, the dog will suffer something similar to what happens to humans after a stroke, where one side of the face can droop.

This nerve failure can be noticed in the dog’s smaller gestures. Among the most obvious signs, we find the following:

• One ear drooping more than the other
• Inability to blink with one of the eyes
• Salivation from one of the corners of the nose
• Difficulty eating
• Peripheral Vestibular Syndrome symptoms. Up to 65% of affected dogs have both conditions at the same time.
• Paralysis of the extremities and stupor, when the injury is central and not only of the nerve.

In most cases of facial nerve damage, paralysis only affects one of the two sides of the face (unilateral), which greatly facilitates the diagnosis. However, if the paralysis is total (bilateral), noticing the signs with the naked eye is very complicated.

Causes of facial paralysis in dogs

As studies indicate, up to 74.7% of cases of facial paralysis in dogs are idiopathic, that is, no cause can be found to explain them. The rate of occurrence of this pathology is difficult to calculate, as a common underlying reason is rarely found.

Beyond unexplored etiologies, the most common causative agent behind facial paralysis is a serious infection in the inner ear (otitis interna), especially in dogs that have chronic skin problems. In these cases, the aforementioned clinical signs are usually accompanied by balance problems and a permanently tilted head.

These are the two most common variants within this condition, but there are other possible causes of partial or total facial paralysis. Some of them are the following:

• A very severe blow, such as a car accident or a serious fall.
• Hypothyroidism, thyroid gland malfunction, and low thyroid hormone production.
• Benign tumors or cancers in the facial area.
• Ingestion of neurotoxins, such as botulinum toxin (botulism).
• Inflammatory or immune-mediated diseases, such as meningoencephalitis.
• Damage after highly invasive cranial surgery.

Diagnosis

Although this condition is more common in its idiopathic variant, it’s still necessary to perform certain tests on the affected animal to rule out other underlying conditions. First, the dog is usually sedated and a deep analysis of the ear of the affected facial plane is performed, in order to rule out the aforementioned ear infection.

If everything is in order in this section, X-rays, computed tomography (CT), and magnetic resonance imaging (MRI) are used for detailed observation of the brain and internal structures of the ear. In rare cases, it may also be necessary to obtain a sample of the canine’s cranial fluids to look for signs of inflammation.

Electrical stimulation of the facial nerve can help quantify damage and establish a prognosis.

Treatment of facial paralysis in dogs

Treatment will be different in each case, but it should be noted that nerve damage is irreversible. This doesn’t mean that you have to give up on your pet, but it does mean you’ll have to accept that it’ll have certain problems from that moment on when it comes to eating and interacting with the environment.

If the cause of the facial nerve damage is a cancerous tumor, surgical resection of the mass and targeted therapy to kill the cancer are usually the options to follow. On the other hand, if the underlying reason is hypothyroidism, the dog will need a lifetime thyroid hormone replacement medication.

If the cause is an infection in the middle or inner ear, a deep cleaning of the ear is usually used initially, through the application of ceruminolytic substances and the extraction of damaged tissues, even under anesthesia and in a local surgical procedure. Once the infected environment has been sanitized, antibiotics or antifungals should be prescribed, depending on the pathogen.

Forecast and final notes

Most of the time, the signs presented are permanent, as the facial nerve suffers irreversible damage and it’s impossible to return it to its previous state. However, this doesn’t usually prevent the dog from leading a normal life, saving certain modifications in the routine.

For this reason, in its idiopathic variant, this condition has a very positive prognosis. However, if the damage has occurred in the brain or the cause is cancer, the condition can become very complicated in a short time. It all depends on the underlying cause.