Veterinary Medicine - November 2007 - (Page 715)

A challenging case O P E E R - R E V I E W E D a recheck 21 days after initial presentation, the IOP was 37 mm Hg in the right eye and 8 mm Hg in the left eye. The patient had become blind in right eye and had bilateral uveitis. The pupils had become irregularly shaped because of posterior synechiae (adhesions between the iris and the anterior lens capsule).2 The cat also exhibited inappetence. The cat was then referred to a veterinary ophthalmologist. OCULAR EXAMINATION The initial ocular examination at The Veterinary Eye Clinic revealed that the right eye was blind and had buphthalmos with iris bombé and posterior synechiae (Figure 1). (Iris bombé occurs when there is forward bowing of the iris and synechiae that seal the iris to the lens so aqueous humor cannot pass through the pupil into the anterior chamber.) The base of the iris had obstructed the filtration angle because of forward bowing of the iris, causing obstructive glaucoma. 3 Fibrin and a blood clot were present in the right pupil (Figure 2). Ulcerative keratitis had developed, likely from exposure, in the right eye. Pars planitis (inflammation of the posterior portion of the ciliary body) was also evident. Uveitis, evidenced by low IOP, was present in the left eye. The left eye also had posterior synechiae and a blood clot in the pupil. The fundus could not be visualized in either eye. The rest of the physical examination findings were normal, and the cat weighed 11.9 lb (5.4 kg). 1. The cat’s right eye exhibited buphthalmos, and the left pupil was irregularly shaped. 2. The cat’s right eye had anterior synechiae and fibrin in the pupil. clude feline infectious peritonitis (FIP), FeLV, and FIV infections. Crypto- DIFFERENTIAL DIAGNOSES Differential diagnoses for uveitis include trauma, systemic infection, neoplasia, and immune-mediated causes. Coagulopathies and systemic hypertension can also cause hyphema. The most common intraocular primary neoplasms are iris melanoma or ciliary body adenocarcinoma.1 Ocular neoplasia can also result from metastatic cancer, most commonly lymphosarcoma. Viral causes of uveitis in cats in- sporidiosis, blastomycosis, histoplasmosis, coccidioidomycosis, and, rarely, candidiasis should be considered depending on the region.4 The algae Prototheca species can also cause uveitis.1 Bacterial causes include Bartonella, Mycoplasma, and Ehrlichia species.4 Toxoplasmosis is a common protozoal cause, which often leads to posterior segment disease, including chorioretinitis and pars planitis. 5 Bartonella henselae and herpesvirus infection have also more recently been implicated as causing uveitis.6 While characteristic signs of specific infectious diseases exist (e.g. pars planitis and chorioretinitis caused by toxoplasmosis), studies have shown that intraocular changes are often indistinguishable among various infectious diseases.7 Specific immune-mediated diseases in the eye include lens-induced uveitis (phacoclastic uveitis), Vogt-KoyanagiHarada-like syndrome, and immunemediated vasculitis. Immune-mediated causes tend to be a diagnosis of exclusion. However, many systemic inflammatory responses (including systemic infection) can also lead to a secondary immune-mediated uveitis. For example, no infectious agents may be identified in the aqueous humor after anterior chamber paracentesis, but uveitis is still present because of systemic infection and activated T cells that have migrated back to the eye.8 A systemic infection was suspected in this cat because there was no known history of trauma, the ocular disease had progressed, and the cat was lethargic and inappetent. The differential diagnoses were bartonellosis, toxoplasmosis, and FIP, FIV, or FeLV infection (although the test results for FIV and FeLV were negative). Other infectious agents were less likely since the cat lived in Colorado9 and had no history of travel. The cat had no intraocular mass and no blood work or thoracic radiograph abnormalities that suggested neoplasia. Because the uveitis was bilateral and the patient had mild lethargy and lymphocytosis, the cause was likely to be idiopathic, immune-mediated, or a manifestation of a systemic disease such as an infection. DIAGNOSTIC TESTS The patient was anesthetized, and anterior chamber paracentesis was performed. Atraumatic tissue forceps were used to grasp the bulbar conjunctiva, and a 27-ga needle was inserted through the perilimbal conjunctiva and limbal cornea to aspirate a small amount of aqueous humor.1 PCR testing was done on the aspirate to evaluate for FIP infection and bartonellosis. In addition, serum was submitted for protein electrophoresis to distinguish between a monoclonal and polyclonal gammopathy as a cause of the VETERINARY MEDICINE November 2007 715

Table of Contents Feed for the Digital Edition of Veterinary Medicine - November 2007

Veterinary Medicine - November 2007 Contents Leading Off The Veterinary Medicine Interview: Dr. Lila Miller Clinical Exposures Idea Exchange A Challenging Case: Uveitis and Secondary Glaucoma in a Cat Is it Immune-Mediated Neutropenia? Pimobendan Treatment in Dogs with Congestive Heart Failure CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller Special Supplement by Lilly: Flea Bite Facts Q&A

Veterinary Medicine - November 2007

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.