Page 2522 - Cote clinical veterinary advisor dogs and cats 4th

Orbital Disorders 1261.e1

Orbital Disorders
VetBooks.ir Type of Disorder Condition Clinical Signs

Developmental abnormalities Shallow orbit (brachycephalic breeds) Exophthalmos, exposure keratitis, corneal ulceration, pigmentation
Microphthalmos, anophthalmia Small or absent globe, narrow palpebral fissure, prominent third eyelid, epiphora,
Hydrocephalus with orbital malformation blindness
Euryblepharon Exotropia, hypotropia, poor vision
Orbital arteriovenous malformation or venous varices Long palpebral fissure resulting in apparent exophthalmos
Exophthalmos may be pulsatile, sometimes varies with position of varices;
fremitus, pulse detectable; arteriovenous malformation has audible bruit
Trauma Hemorrhages Subconjunctival and episcleral hemorrhages; retrobulbar hemorrhage with
Penetrating foreign bodies (e.g., grass awns, needles, exophthalmos or proptosis
from mouth) Discharging sinus fluid through the conjunctiva, periocular skin, buccal mucosa;
Orbital fractures exophthalmos, periorbital swelling, pain on opening of mouth
Acquired vascular shunts Pain, crepitus; skin abrasions, displacement of globe
Pulsatile exophthalmos, may vary with position; audible bruit, fremitus
Infections Bacterial, fungal Ocular discharge usually secondary to penetrating foreign bodies from conjunctiva
Parasites (Dirofilaria immitis; Pneumonyssoides or oral cavity; sinusitis, rhinitis, or infections of roots of teeth
caninum) Granulomatous lesions due to wandering larvae (Dirofilaria [rare]) or extension of
infection from nasal cavity (Pneumonyssoides)
Neoplasia Primary orbital neoplasms and neoplasia extending Exophthalmos, exposure keratitis, strabismus, displacement of globe, usually not
from adjacent area: sarcoma, meningioma, painful; possible nasal or neurologic signs
adenocarcinoma from orbital glands or nasal cavity, Localized signs as already listed; possible systemic signs
lymphosarcoma in cats
Metastatic: includes lymphoma
Miscellaneous conditions Zygomatic mucocele/sialocele Exophthalmos, strabismus, swelling in any part of orbit or behind upper last molar Differentials, Lists, and Mnemonics
Infections of roots of teeth (especially carnassial) tooth
Dehydration Discharging fistula ventral to the eye in dogs
Masticatory myositis Enophthalmos, protrusion of third eyelid
Extraocular polymyositis Exophthalmos, pain with dysphagia in acute stage; enophthalmos potentiated by
Horner’s syndrome opening of mouth in chronic stage when temporal muscles have atrophied
Exophthalmos, often bilateral, may be accentuated with exercise and stress
Enophthalmos, miosis, ptosis, protrusion of nictitating membrane, dermal
vasodilation, local hypothermia
From Maggs DJ, et al: Slatter’s fundamentals of veterinary ophthalmology, ed 4, St. Louis, 2008, Saunders, p 362.

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