Horner’s Syndrome is a common neurological disorder that affects the eye. A combination of signs can occur caused by the disruption of a nerve pathway from the brain to the eye and surrounding structures on one side of the body.


Most commonly, we do not find an underlying cause of Horner’s Syndrome, though there are several reasons a dog can develop it. Potential causes include:

  • Trauma to the neck caused by anything from traffic accidents to choke collars
  • Bite wounds around the head and neck
  • Middle ear disease, also known as an ear infection
  • Brain or spinal cord tumors
  • Spinal cord injury or intervertebral disc disease
  • Metabolic diseases such as hypothyroidism or diabetes

Signs and Symptoms

Horner’s Syndrome manifests itself into quite distinctive clinical signs, which include:

  • Drooping of the eyelid
  • Constricted pupil on the affected side
  • Appearance of a sunken eye
  • Redness of the eye
  • Protrusion of the third eyelid

If you recognize these signs in your dog, see your primary veterinarian for a thorough exam, diagnostic testing and blood work. Based on their findings, they may refer you to a veterinary neurologist or ophthalmologist.


Treatment options vary case by case and are based on the underlying cause of Horner’s Syndrome in each pet. If there is no pathological cause, the disease is typically self-resolving. In idiopathic cases (no cause determined) there is no treatment.

Diagnostic tests such as blood work, chest x-rays, spinal x-rays, or MRI can help determine if there is a treatable condition causing Horner’s Syndrome. A neurologist and/or ophthalmologist may be consulted if necessary.

A Few Things to Know

  • It is not a painful condition, nor does it affect vision
  • All dogs are susceptible, though Golden Retrievers and Cocker Spaniels have a higher incidence
  • There is no way to prevent Horner’s Syndrome


If your primary veterinarian diagnoses your pet with a neurological or ophthalmological disorder that is causing Horner’s Syndrome, CARE specialists and staff will work with your veterinarian to provide the best treatment for your pet. Ask your vet to schedule a consultation with Dr. Amy Fauber or Dr. Joshua Broadwater, based on your pet’s specified needs.

CARE’s Neurology service focuses on diseases affecting the brain, spinal cord and nerves. As a board-certified neurologist, Dr. Amy Fauber has received specialized training in both medical and surgical neurologic conditions.

CARE’s Ophthalmology service focuses on treating eye diseases in dogs and cats to restore vision and prevent painful eye conditions. Dr. Joshua Broadwater is our board-certified ophthalmologist.

For emergencies and outside business hours, CARE’s Emergency service is available 24/7/365. Call us at 704.457.2300 or bring your pet to 3726 Latrobe Drive in Charlotte, North Carolina.

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