Canis ISSN: 2398-2942

Retrobulbar space-occupying lesions

Contributor(s): Dennis E Brooks, David L Williams, James Oliver


  • Cause: abscess/cellulitis, neoplasia, cysts and mucocele, extraocular polymyositis, masticatory muscle myositis, hemorrhage, craniomandibular osteopathy, vascular anomalies.
  • Signs: exophthalmos, strabismus, globe indentation, nictitans protrusion, difficulty or discomfort on opening mouth, red eye, restriction of globe retropulsion, unilateral nasal discharge/blockage.
  • Diagnosis: ultrasonography, advanced imaging (CT/MRI), fine needle aspiration biopsy.
  • Treatment: depends on cause. Drainage and antibiotics and anti-inflammatories for abscess, surgery/chemotherapy/radiation therapy for neoplasia, immunosuppressive agents for extraocular polymyositis and masticatory muscle myositis.
  • Prognosis: good for abscess/cellulitis, cysts and mucoceles, guarded-fair for extraocular polymyositis and masticatory muscle myositis, usually poor for neoplasia.



  • Abscess/cellulitis.
  • Neoplasia.
  • Cysts/mucoceles.
  • Extraocular polymyositis.
  • Masticatory myositis.
  • Vascular anomalies.
  • Craniomandibular osteopathy.


  • Abscess/cellulitis:
    • Hematogenous dissemination.
    • Penetrating injury.
    • Foreign body.
    • Tooth root abscess.
  • Neoplasia:
    • Primary - arising from any orbital tissue.
    • Secondary - extension from neighbouring tissue or metastasis.
    • Usually malignant.
  • Myositis:
    • Immune-mediated inflammatory myopathy.
  • Cysts:
    • Dermoid:
      • Congenital.
    • Salivary retention cysts:
      • Result from inflammation of oral mucosa and obstruction of salivary flow.
  • Mucoceles:
    • Sialoceles:
      • Usually result from trauma.
  • Vascular anomalies:
    • Congenital or acquired.
  • Craniomandibular osteopathy:
    • Inherited.
  • Hemorrhage:
    • Trauma.



  • Varies depending on cause.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lederer K, Ludewig E, Hechinger H et al (2014) Differentiation between inflammatory and neoplastic orbital conditions based on computed tomographic signs. Vet Ophthalmol 18 (4), 271-275 PubMed.
  • Armour M D, Broome M, Dell'anna G et al (2011) A review of orbital and intracranial magentic resonance imaging in 79 canine and 13 feline patients (2004-2010). Vet Ophthalmol 14 (4), 221-226 PubMed.
  • Håkansson N W & Håkansson B W (2010) Transfrontal orbitotomy in the dog: an adaptable three-step approach to the orbit. Vet Ophthalmol 13 (6), 377-383 PubMed.
  • Wang A L, Ledbetter E C & Kern T J (2009) Orbital abscess bacterial isolates and in vitro susceptibility patterns in dogs and cats. Vet Ophthalmol 12 (2), 91-96 PubMed.
  • Wu X, Li ZF, Brooks R et al (2007) Autoantibodies in canine masticatory muscle myositis recognize a novel myosin binding protein-C family member. J Immunol 179 (7), 4939-4944 PubMed.
  • Atali-Soussay K, Jegou J P, Clerc B (2001) Retrobulbar tumours in dogs and cats: 25 cases. Vet Ophthalmol 4 (1), 19-27 PubMed.
  • Dennis R (2000) Use of magnetic resonance imaging for the investigation of orbital disease in small animals. JSAP 41 (4), 145-155 PubMed.
  • Hendrix D V & Gelatt K N (2000) Diagnosis, treatment and outcome of orbital neoplasia in dogs: a retrospective study of 44 cases. JSAP 41 (3), 105-108 PubMed.

Other sources of information

  • Gelatt K N (1999)Veterinary Opthalmology.3rd edn. Lippincott, Williams & Wilkins.