Veterinary Medicine - November 2007 - (Page 718)

A challenging case O P E E R - R E V I E W E D iris color change (usually to a darker shade), keratic precipitates (deposition of inflammatory cells on the corneal endothelium), miosis, and pain.1 Decreased IOP occurs when the ciliary body becomes inflamed, decreasing aqueous humor production and increasing perfusion through the posterior vascular pathway. In acute uveitis, blepharospasm, enophthalmos, and elevation of the third eyelid are common. With chronic uveitis, these manifestations of ocular pain may no longer be present. Patients with chronic uveitis may also present with posterior synechiae. Iris bombé and glaucoma can occur, as seen in this cat. 3. The cat’s left eye remains visual but the pupil is irregular in shape because of posterior synechiae, where portions of the iris have attached to the anterior lens capsule. Work-up for feline uveitis Always investigate uveitis, as cats with systemic and fatal diseases may present with only uveitis.15 In one study of 124 cats with uveitis, serologic evidence of infectious agents was found in 83% of the samples.16 Other studies indicate that systemic disease is present in 25% to 90% of cats with uveitis.2 Initially test any cat with uveitis of unknown cause for FIV and FeLV infections, and ask the owner about travel, trauma history, vaccination status, and whether the cat goes outdoors. Additional diagnostic tests when systemic causes are suspected include a complete blood count, a serum chemistry profile, and a urinalysis. Fungal antibody titers and antibody titers against Toxoplasma gondii also may be useful. Anterior chamber paracentesis with PCR and culture of the aqueous humor for Bartonella species, coronavirus, T. gondii, and Cryptococcus species are helpful. A Western blot may be performed to look for Bartonella species.5 Even with an exhaustive diagnostic work-up, a definitive cause may not be found.6 This patient had anterior uveitis and developed secondary iris bombé, glaucoma, and finally blindness. This progression illustrates the importance of early recognition and treatment of uveitis. When inflammation compromises the integrity of the blood-ocular barrier, proteins, fibrin, and blood leak into the aqueous humor and the vitreous. Synechiae and glaucoma can follow. Glaucoma can also occur when inflammatory mediators affect the trabecular endothelium and physically obstruct the filtration angle or block aqueous flow through the pupil.2 Treating uveitis When uveitis is recognized, administer atropine to dilate the pupil to avoid synechiae and administer topical (e.g. diclofenac) and systemic anti-inflammatory medications to avoid complicating sequelae. Anti-inflammatory medications are the mainstay of treatment for uveitis. The treatment goals for any uveitis case are to block prostaglandin formation and other mediators of inflammation, reduce painful ciliary spasm, dilate the pupil to prevent synechiae and secondary glaucoma, and restore the bloodaqueous and blood-retinal barriers.12 Thoughtful use of atropine is important because overuse can decrease tear production and cause glaucoma. The idea is to keep the pupil moving; do not simply administer atropine twice daily but rather wait until the pupil begins to constrict before repeat dosing. Glaucoma results when mydriasis further reduces the outflow of aqueous humor due to the accumula- 718 November 2007 VETERINARY MEDICINE http://www.reconcile.com

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

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