Exophthalmos – Rabbit

Introduction

Exophthalmos is the most prevalent clinical sign associated with orbital disease.

This may be a gradually worsening disease or may present as an emergency. It may signal a retrobulbar infection which may be diagnosed and cured, or an retrobulbar neoplasm difficult to diagnose and treat.

The exposed eye can easily be damaged due to its vulnerable state, and the appearance of the eye can be an unpleasant experience for the owner.

Causes

In rabbits, unilateral exophthalmos may be caused by:

Retrobulbar abscess: Pasteurella has frequently been implicated as the cause of these abscesses, although culture is rarely performed. Due to the close apposition of the globe to the posterior dental molar roots, dental disease and root infection can lead to severe exophthalmos.

Orbital cellulitis

Orbital cyst

Retrobulbar fat prolapse

Salivary mucocoele

Retrobulbar neoplasia

Taenia serialis - coenurosis

Bilateral exophthalmos may be caused by the above occurring bilaterally and also by:

Thymoma

Mediastinal lymphoma

Long-term external jugular catheter placement

These are as a consequence of increased pressure on the jugular vein.

Investigation

A full clinical examination is vital.

Ocular examination is very important, as well as a full cranial examination including a dental examination to detect any abnormalities.

Skull radiography may reveal tooth root infections, molar overgrowth, or bone destruction due to an aggressive tumour.

CT and MRI can also be considered in some cases.

Ocular ultrasonography can also be useful in diagnosing retrobulbar conditions.

Any masses may be aspirated or biopsied, and cytology, culture and sensitivity may be performed to determine the cause of the presentation.

Treatment

The main treatment will depend on the underlying cause of the disease and is not covered here.

General treatment for a rabbit with exophthalmos should include:

artificial tear ointment every 6 hours to help lubricate the eye and prevent desiccation and ulceration

topical antibiotics and an iridocycloplegic such as atropine, if ulceration is present

pain management: NSAIDs are very useful for the long-term control of pain. Meloxicam or carprofen have been used.

Exophthalmos – Rabbit Learning Resources
Flashcards Test your knowledge using flashcard type questions	Rabbit Medicine and Surgery Q&A 13

References

Maggs, D. (2008) Slatter's fundamentals of veterinary ophthalmology Elsevier Health Sciences

Oglesbee, B. (2006) The 5-minute veterinary consult: ferret and rabbit Wiley-Blackwell

Williams, D. (2002) Veterinary ocular emergencies Elsevier Health Sciences

Vernaue et al (1995) Thymoma in a geriatric rabbit with hypercalcaemia and periodic exophthalmia J Am Vet Med Assoc 206 820-822

Wagner F et al (2005) Recurrent bilateral exophthalmos associated with metastatic carcinoma in a pet rabbit Journal of Small Animal Practice 46, 393-397