For most dogs, the signs associated with idiopathic Horner’s syndrome will resolve within 4 to 6 months. Luckily for your pet, Horner’s syndrome itself is not painful (although the underlying cause may be). In some cases, Horner’s syndrome will interfere with your dog’s vision because the eye is covered by the third eyelid, but if that is not the case, most dogs are not significantly affected by the condition.
If your dog’s Horner’s syndrome does not have a definitive cause, and is determined to be post-ganglionic (which is most common) only time will resolve the condition. The symptoms, however, may be reversed temporarily by the use of eye drops two or three times daily. This is only recommended if the symptoms are affecting the vision, as they lose effectiveness with continued use. It is important to know that the eye conditions resulting from Horner’s syndrome are due to a nerve problem that is not painful.