Horner’s syndrome is a common neurological disorder of the eye and facial muscles and can occur suddenly. Dysfunction of the sympathetic nerves of the eyes and surrounding facial muscles causes Horner’s syndrome and may be due to an injury such as a bite wound or blunt trauma, a tumor, intervertebral disc disease, or middle or inner ear disease.
https://vcahospitals.com/know-your-pet/horners-syndrome-in-cats

