b'YOUR GUIDE TO THE 2017 AAEP CONVENTION SPONSORED BYloss of use. Adding insult to injury, the disease keeps coming back, often result-ing in blindness. Recognizing and Treating Corneal Stromal This condition frequently frustrates vet- Abscesses in Horseserinarians such as Mary Lassaline, DVM, PhD, MA, Dipl. ACVOeven to the pointWhen a horse has an angry eye, its often due to a defect involving the surface, known as of despair, she saidbecause it remainsa corneal ulcer. Other times, however, a painful eye could reveal a deeper problema corneal expensive and unrewarding to treat. Butstromal abscessa condition equine ophthalmologists dont want veterinarians to forget as researchers learn more about the insabout. Dennis Brooks, DVM, PhD, Dipl. ACVO, described deep stromal abscesses (DSAs). and outs of ERU, theyre finding ways toTo briefly review: The corneathe outer window that admits light to the eyeconsists of improve treatment. several layers. On the outer surface, eight to 12 layers of epithelial tissue make up 15% of ERU is the No. 1 cause of blindnessthe total corneal thickness. Underneath lies a thicker layer called the stroma, followed by Descemets membrane, which is a single layer of endothelium (thin skin cells, essentially) that comes with important emotionalthat covers the corneas inner surface.and economic strings attached, saidAbscesses of the stroma are usually not ulcerated, said Brooks, founder of the equine Lassaline, a large animal ophthalmologistophthalmology consulting firm BrooksEyes LLC. Instead, horses typically present with pain-at the University of California, Davis. Inful uveitis or inflammation of the uvea. The uvea provides nutrition to various parts of the eye one retrospective study, approximatelyand, if inflamed, can cause painful blindness. 15% of affected horses are euthanized,Brooks stated that DSAs can form in a number of ways. For example, they can develop and by the time many horses are referredsecondary to a corneal ulcer when an infectious agent or foreign body becomes trapped in to a specialist, the horses disease is al- the stroma while the ulcer heals. Alternatively, a horse could develop a DSA after trauma to ready at an advanced stage. Up to 25% ofthe eye that causes micropunctures, which allow bacteria or fungi to enter the stroma, even horses are already blind by the time theywithout creating a corneal ulcer. are referred. Veterinarians can recognize a stromal abscess in horses with a painful eye and a focal In that same retrospective study, many(single, distinct) yellow-white circular infiltrate in the corneal stroma, together with corneal horses with ERU already underwent a ca- edema (swelling). Sometimes, several abscesses can occur at the same time.reer change or had reduced activity, andWhen examining the eye, if you see a fernlike frond or a collection of red blood vessels about 50% tested positive for leptospi- in a focal area, there is a reason they are there. To fully examine that eye you need to see rosis, a bacterial disease that can causepast them, Brooks told conference attendees. Simply apply some phenylephrine or epi-chronic uveitis, she added. nephrine (to constrict blood vessels) to blanch them out to properly examine the patient to To review, ERU is a painful immune- see if an abscess is behind the blood vessels.mediated form of uveitis inflammationIn terms of treatment, always start with medical therapy, Brooks advised. These corneal of the uveal tract, which comprises theabscesses are very thick and not amenable to draining.iris, muscular ciliary body, and choroid.Recommended treatment involves administering a combination of antimicrobials (includ-Chronic uveitis can cause permanenting antifungals), anti-inflammatories, and pupil-dilating agents. Subpalpebral lavage sys-tems can help owners manage abscesses in the field; treatment might need to be applied changes in the eye, including cataracts,four to six times daily for four to six weeks or longer.glaucoma, and retinaldetachment.These take weeks to heal, Brooks said. During this process, we want the abscess to There are multiple causes for ERU,turn white, not orange. The goal is to have the uveitis and flare dissipate and the blood ves-and despite the importance of thissels disappear. If you see orange, refer the case immediately.Stacey Oke, DVM, MScdisease, ERU remains incurable, said Lassaline. In light of these facts, she encouraged practitioners to approach horses withthat has a camera plus the light to per- Cyclosporine implants, which veterinari-painful eyes in a systematic and stan- form a fundic exam easily and thorough- ans place in the eye surgically, can reduce dardized fashion to optimize chances ofly, Lassaline said.the frequency and severity of ERU flare-treatment success:For a veterinarian to diagnose ERU,ups and can last for at least 48 months. Recognize uveitis promptly.1.It is charac- the horse must have uveitis that has re- Wrapping up, Lassaline reminded terized by miosis (excessive constrictioncurred or is persistent. Veterinarians useveterinarians that commercially available of the pupil); a painful, red, and cloudya standardized grading scheme for ERUleptospirosis vaccines are not labeled to eye; and low intraocular pressure.(e.g., on a scale of 1 to 5) to make an earlyprevent or treat ERU. hStain every eye.2.Corneal ulcers candiagnosis and assess treatment success.also cause squinting, tearing, redness,In some ways, ERU is akin to lamini-and cloudiness. Staining the eye withtis, a recurrent and lifelong, life-altering a fluorescent dye can distinguish themcondition, said Lassaline.efrom uveitis. For treatment, Lassaline recommendedVisit TheHorse.com/AAEP2017Always do a fundic exam3.to assess theadministering topical steroids, topicalstructures in the back of the eye.atropine to dilate the eye, and systemic Corneal Ulcer Cytology: How and Why, You can use a smartphone and an appnon-steroidal anti-inflammatory drugs.TheHorse.com/40215A42 TheHorse.com/AAEP2017 AAEP Wrap-Up THE HORSEMarch 2018'