An eye on canine orbital disease: Causes, diagnostics, and treatment
An 8-year-old spayed female miniature poodle was presented to a veterinary clinic in Colorado with the complaint of a swollen right eye, which had been present for several days. The dog's pulse and respiration rate were normal, but its temperature was slightly above normal at 102.6 F (39.2 C). The physical examination findings were normal except that the right eye was exophthalmic and the third eyelid was protruding halfway across the cornea. Additionally, the dog cried out in pain when its mouth was manually opened.
The clinical signs exhibited by this dog could be grouped together into one etiology—orbital disease. There are many causes of orbital diseases, including a retrobulbar, space-occupying mass (orbital abscess, cellulitis, cyst, or neoplasm); myositis; or an orbital vascular anomaly.1-20
CANINE ORBITAL DISEASE OVERVIEW
Foreign bodies and abscesses
Foreign bodies may enter the orbit through the conjunctiva or the roof of the mouth. Many types of orbital foreign bodies have been reported, including grass awns, porcupine quills, gunshot pellets, and wood slivers and chunks.4-8
Foreign bodies can cause cellulitis and abscessation.4-8 Dogs with orbital foreign bodies may present with some degree of exophthalmos, protrusion of the third eyelid, and severe pain on opening of the mouth.2 Purulent to mucopurulent ocular discharge and conjunctival and episcleral injection may be present, although the globe itself, if not penetrated by the foreign body, is often normal. The dog may be febrile if an abscess is present. Younger dogs are more commonly affected as they have a greater likelihood of chewing foreign objects.
In a retrospective study of 34 dogs and seven cats with orbital abscesses, the most common route by which bacteria entered the orbits was through extension from adjacent infected structures, foreign bodies, and penetrating trauma.3
Of the 34 dogs, about 60% had positive bacterial culture results. The most frequently cultured bacteria were of the genera Staphylococcus, Clostridium, Escherichia, Bacteroides, and Pasturella. Most of the aerobic organisms were susceptible (in vitro) to many antibiotics, including amikacin, ceftiofur, gentamicin, imipenem, ticarcillin, and trimethoprim-sulfamethoxazole.3