Horner's syndrome

Horner’s syndrome is a name given to a group of eye signs seen in affected patients associated with damage to a long (3 part) nerve called the sympathetic trunk. The sympathetic truck is part of our fright / flight reflexes (dilated pupil, forward positioned globe, wide open eyelids) and when damaged these reactions do not occur. Signs seen in affected patients often include mild drooping of the upper and lower lids, a small diameter pupil, and prominent third eyelid.

Causes are frequently unknown (idiopathic), but may include trauma (check chain injuries), infections, ear conditions, inflammation, and tumours. Damage may occur along any of the 3 part of the nerve, but the end closest to eye is the most common area affected.  During examination for Horner’s syndrome at the Auckland Animal Eye Centre, a medication will often be dropped on the eye in an attempt to locate the area of nerve damage.

The middle aged Golden Retriever dog is the most common patient referred to this clinic with Horner’s syndrome, and when not associated with other diseases, Horner’s syndrome usually resolves within months.