Canis ISSN: 2398-2942

Horner syndrome

Synonym(s): Claude Bernard-Horner syndrome; Horner's syndrome

Contributor(s): Dennis E Brooks, Laurent Garosi

Introduction

  • Common unilateral neurological disorder of eye - can sometimes be bilateral.
  • Cause: most common cause is idiopathic Horner syndrome - potentially lesion anywhere along the sympathetic pathway to the eye (brainstem, cervical spinal cord, T1-T3 spinal cord, brachial plexus, intrathoracic, vagosympathetic trunk, middle ear, retrobular).
  • Signs: ptosis upper eyelid, miosis, enophthalmos, protrusion of third eyelid (due to enophthalmos and nictitans muscle relaxation in cats), conjunctival hyperemia in some animals.
  • Diagnosis: sometimes can identify location of injury pharmacologically, more usually by other associated clinical signs.
  • Treatment: specific treatment for underlying disease if it can be ascertained; clinical signs can often be improved with topical phenylephrine.
  • Prognosis: can recover over protracted period, depending on site and nature of lesion.
    Follow the diagnostic tree for Horner Syndrome Horner Syndrome.

Pathogenesis

Etiology

Predisposing factors

General
  • Dogs with a tendency to develop spinal cord and middle ear disease are at risk.

Pathophysiology

  • Pathological change at one of several sites → failure of sympathetic nerve supply to eye and surrounding structures → loss of smooth muscle tone → clinical signs.
    • First order: hypothalmus to T1-T3 spinal cord lesions.
    • Second order: thoracic sympathetic trunk to cranial cervical ganglion lesions.
    • Third order: post-ganglionic fibers arising at cranial cervical ganglion rostrally up to the eye.

Timecourse

  • Slow recovery over many months depending on etiology and treatment.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Simpson K M, Williams D L, Cherubini G B (2015) Neuropharmacological lesion localisation in idiopathic Horner's syndrome in Golden retrievers and dogs of other breeds. Vet Ophthamol 18, 1-5 PubMed.
  • Spivak R E, Elkins A D, Moore G E et al (2013) Postoperative complications following TECA-LBO in the dog and cat. JAAHA 49, 160-168 PubMed.
  • Boydell P (2000) Idiopathic Horner syndrome in the golden retriever. J Neuroophthalmol 20, 288-290 PubMed.
  • Boydell P & Brogan N (2000) Horner's syndrome associated with Neospora infection. JSAP 41 (12), 571-572 PubMed.
  • Boydell I P (1998) Horner's syndrome in a puppy. JSAP 39 (9), 448-9 PubMed.

Other sources of information

  • Garosi L, Lowrie M (2014) Neuro-ophthalmology. In: BSAVA Manual of Ophthalmology. 3rd edn. Gould D & McLellan G (eds). BSAVA.
  • Gelatt K N (1999)Veterinary ophthalmology.3rd Edn. Williams & Wilkins.


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