Orbital Cellulitis and Intraocular Abscess by Foreign Body (Plant Material) in a Cat: Case Report
A domestic shorthaired cat, four-month-old, male neutered, was referred to the 0phthalmology Service at the Veterinary Teaching Hospital of Murcia with a week history of ocular pain and swelling, anorexia and lethargy. Physical examination confirmed that clinical abnormalities were limited to the right eye and orbit.
The ophthalmic examination confirmed purulent and haemorrhagic discharge, third eyelid protrusion, chemosis and anisocoria with right miosis. The fotomotor reflexes revealed a negative right direct and consensual and left consensual pupillary light reflex. The intraocular pressures were 8 and 13 mm Hg in the right and left eye respectively, by applanation tonometry. Biomicroscopy revealed mild corneal edema, stromal vascularization, marked aqueous flare and miosis. Direct and indirect ophthalmoscopy examination were not possible, due to the opacity of the transparent media. An ocular and orbital ultrasonography using high frequency ultrasound transducer of 7'5 MHz was performed. The retrobulbar echogenicity was altered. Linear and round structures very well defined and markedly hypoechoic which indented the globe, were seen. This ultrasonogram is compatible with an accumulation of retrobulbar fluid. Skull Radiography was done and no abnormality was detected. Drainage via pterygopalatina fossa was performed. A hematological analysis showed neutrophilic leukocytosis. The tentative clinical diagnosis was orbital abscess and cellulitis. The cat was treated with enrofloxacin and metil prednisolone administered PO q24h. Tropicamide and dexamethasone drops q8h. The cat was reexamined 3 days later and marked ocular improvement was noticed. The bacterial culture revealed Staphylococcus spp. sensitive to enrofloxacin. Five days later the cat became suddenly depressed. The eye evidenced a deterioration with increased episcleral congestion, increased corneal edema and vascularization. Indirect ophthalmoscopy revealed retinal detachment and vitreous haemorrhage. The ocular ultrasonography showed now a hyperechogenic area in the vitreous and a retinal detachment. Failure on medical treatment for infection control and intraocular damage with poor visual prognosis, made enucleation the only therapy for this case. The etiologic diagnosis was possible thanks to a fortuitous finding during surgery. A purulent content and grass awn was found. The grass awn penetrated into the sclera causing a suprachoroidal abscess.
Intraocular and intraorbital foreign bodies are frequently the cause of losing the vision and the ocular structure. They have previously been reported in the dog but it is unusual in the cat. They include plant material, wood splinters, glass, gunshot pellets, metallic fragments, bone, tooth fragments and porcupine quills (Grahn et al. 1995). Ocular reaction to a retained foreign body depends on the size and composition of the foreign body, the tissue in which it lodges, and its mechanical irritation (Schmidt et al. 1975). Intraocular or intraorbital foreign bodies that are inert and inaccessible, where removal would be excessively traumatic, should be left in situ (Schmidt et al. 1975). Plant materials are not inert, as they may harbor bacteria, be directly irritating, and evoke a septic or sterile foreign body reaction, and result in chronic infection with abscess or fistula formation (Bussanich and Rootman 1981, LoBue et al. 1988). Most ocular diseases associated with plant material affect the conjunctiva, nictitating membrane, and cornea. Occasionally plant material may penetrate the cornea (Bussanich and Rootman 1981), it also may penetrate the eye directly by migration into the orbit from periocular tissues or through the mouth. In our case, the posterior area of ocular disruption suggests the latter as the likely route from which the grass penetrated the eye. The point of the grass awn favors its penetration into the dense collagenous tissue of the sclera. The chemical nature, size, position, as well as, the therapy and visual prognosis of the foreign bodies are determined by ophthalmic examination and imaging diagnostic. Radiography can be used to detect metallic foreign bodies, but metallic or non metallic foreign bodies within or around the eye can be imaged with ultrasound (Scmidt et al. 1975, McElvanney and Fielder 1993, Mattoon and Nyland 1995). However in our case, the plant material was not identified by ultrasonography. High-resolution CT scanning may fail to identify organic foreign bodies such as wood and vegetable matter, thus, magnetic resonance imaging is an alternative to ultrasound and CT in this setting (LoBue et al. 1988 and Dennis 2000). Ultrasonographic pattern found, revealed an orbital area markedly hypoechoic with linear and round structures which suggests cellulitis and abscessation secondary to septic plant material reaction and its migration into the orbit. Second examination showed a hyperechogenic image in the vitreous and a complete loss of the ocular structure accompanied by clinical symptoms exacerbation. Hyperechoic material in the vitreous chamber is representative of old inflammation or infection, fibrosis or mineralization (Mattoon and Nyland 1995). Failure on medical treatment and intraocular lesion showed by ultrasonographic and ophthalmoscopic exam, led to enucleation. Observation of the vegetal awn led to the etiological definitive diagnostic only suspected to this stage, according to signs, clinical history and failure on treatment. Histopathology study showed an intraocular abscessation with implication of sclera, choroides and retina (Bussanich and Rootman 1981).