Facial Nerve Paralysis

Facial nerve paralysis describes a loss of normal movement on one side of the face, caused by disruption to the nerve that controls the muscles of facial expression. The facial nerve also carries fibres responsible for tear production and some aspects of taste, so changes in these functions can occur alongside the visible asymmetry. Owners often notice that one side of the face appears drooped or slack, that the ear on the affected side hangs lower, or that the eye on that side does not blink normally. Drooling from one side of the mouth, difficulty holding food, or a change in the shape of the muzzle when the dog or cat is at rest may also prompt concern. In some cases the onset follows an ear infection or head trauma, but in many animals no clear trigger is identified. This page explores the patterns that suggest facial nerve involvement, the mechanisms that can disrupt the nerve's function, the investigations used to clarify the picture, and the range of approaches taken when managing the condition and its effects.