This is a general description of Horner's Syndrome. Due to the nature of this disorder it is difficult to discuss treatment options and
prognosis without first trying to determine what is the cause of HS. If you have more questions or wish to discuss your dog's case
in further detail post again and I will see what I can do. Fortunately this is not a real common disorder and the cases I have seen in
my practice responded very well by treating them the way I described. I hope you find this information useful.

Horner’s Syndrome:

Horner’s syndrome in dogs is a disorder that involves the loss of the sympathetic innervation to the eye and periorbita (tissue
structures around the orbit or eye socket). It can cause the following clinical signs. 1. Miosis (contraction of the pupil) and
Anisorcoria (inequality of the diameter of the pupils) 2. Enopthalmos (sinking or retraction of the eye back into the socket) 3.
Ptosis (drooping of the upper eyelid) 4. Nictitans protrusion (the more prominent appearance of the third eyelid in the corner of the
eye closest to the nose) These are what we call the cardinal signs of Horner’s Syndrome. Enopthalmos, ptosis, and nictitans
protrusion are often very subtle and less noticeable than the miosis. The owner most often recognizes the difference in the diameter
of the pupils first.

The onset of Horner’s Syndrome (HS) is most often very acute. In order for the diagnosis to be confirmed at least 3 of the 4
clinical signs must be present. There are many causes of HS such as trauma, neoplasia (cancer), infectious or inflammatory
disease, thoracic masses, abscesses, bite wounds to the neck, middle ear infections, hypothyroidism, and idiopathic (means the
cause is unknown) to name a few. Basically what is involved is damage to or pressure exerted on the sympathetic nerve system as
the cervical sympathetic nerve courses from the brain to the chest area and back to the eye socket area. I have treated a few cases
of HS in my practice and all have responded well to treatment with 1% Phenylephrine solutions and corticosteroid therapy.
However due to the many causes of HS this will not be a successful treatment of all cases. I should also mention that many cases
of HS will spontaneously resolve in 6 to 8 weeks. In the cases I treated the cause in all cases was determined to be due to improper
use of a choke collar. The clients had used a choke type collar to restrain the dogs and when they lunged excessively after being
tied out on a leash they caused damage to the nerve in the neck area. I have also seen cases of HS secondary to ear infections as a
secondary problem that cleared up after the ear infection was properly treated. It is important to note that cases of HS caused by
lesions that cause damage to the cervical sympathetic nerve in the brain stem area have a much less favorable prognosis than the
others.
 

DR.J
Good Luck and Good Hunting!!!!!!!!!!!!!!!!!!!!!!!!