Facial Palsy

Facial palsy (also: facial paralysis) is the medical term for paralysis of the nervus facialis, i.e., the seventh cranial nerve. This nerve controls the mimetic muscles in the face, both in humans and in animals such as dogs or cats.

What is the facial nerve?

The nervus facialis is responsible for many important functions, including:

• Movement of the facial muscles (e.g. eyelid closure, frowning, lip movement)
• Partial sense of taste
• Control of small muscles in the ear area
• Involvement in tear and saliva production

Facial Palsy in Dogs: Symptoms

Facial palsy in dogs can occur unilaterally or bilaterally. Typical signs:

• Drooping ear on one side
• Drooping lip, possibly increased salivation
• Incomplete eyelid closure (→ risk of lagophthalmos and corneal damage)
• Asymmetrical facial expression
• Watery eye, as the tear film is not distributed properly
• In severe cases: problems drinking or eating

Causes of Facial Palsy

• Idiopathic, i.e. without an identifiable cause (most common case in dogs)
• Inflammations (e.g. otitis media)
• Trauma (e.g. after an accident or bite wound)
• Tumours in the area of the skull bone or ear canal
• Neurological conditions
• Surgery or injections in the head area

Why a cause is often not identifiable

In dogs, idiopathic facial palsy is indeed the most common form, meaning that the exact cause often cannot be clearly determined.

This is mainly because the nervus facialis is very susceptible to various types of damage that are not always clearly detectable through typical symptoms or imaging procedures. Many cases arise suddenly and without identifiable triggers such as trauma, infections, or tumours. This leads to vets finding no specific cause, thus using the term “idiopathic”.

Treatment and Prognosis

The fact that diagnosis is often difficult and many cases fall under “idiopathic” does not mean at all that one should simply “wait and see”: A thorough veterinary examination is essential to rule out treatable causes and protect the eye in the long term.

Therapy depends on the cause. Possible measures include:

• Anti-inflammatory medication
• Antibiotics (for bacterial causes)
• Eye protection, e.g. with eye ointments or tarsorrhaphy, if the eyelids do not close properly
• Surgical intervention if tumours or middle ear changes are present

Prognosis

• In idiopathic facial palsy: often good chances of spontaneous healing within a few weeks
• In structural causes: dependent on the extent of the damage

Conclusion

Facial palsy is a serious condition, primarily because it can endanger the eye. It occurs more frequently in dogs than in cats and always requires veterinary investigation.