Horner’s syndrome in dogs and cats – a review

In dogs and cats, Horner's syndrome is characterized by a group of clinical signs arising from an ipsilateral dysfunction of sympathetic innervation of the eye and its appendages. These signs include ptosis, miosis, anisocoria, prolapse of the third eyelid, and enophtalmos. Lesions that may affect directly or indirectly the sympathetic innervation of the eye, such as trauma, neoplasms, iatrogenic lesions, otitis, encephalitis, among others, can induce HS. The aim of the present study was to review the anatomical and physiological characteristics of sympathetic innervation for the ocular globe, with emphasis on the description of the peculiarities of HS, including its etiology, clinical signs, diagnostic tools, as well as its possible treatments and prognosis.