Equine Health Update EHU Vol 20 Issue 01 - Page 49

EQUINE | Equine Disease Update common. These ulcers are very similar to those in small animals – Spontaneous Chronic Corneal Epithelial Degeneration [SCCED]. The lesion is also usually unilateral, centrally or paracentrally located and a halo of loose epithelium is visible around the lesion. The affected eye usually has little neovascularisation present, some oedema is usually seen around the lesion and the eye is painful. There may be bouts of intermittent healing. The non-adherent epithelial edges can be identified by infiltration of fluorescein underneath the epithelium surrounding the erosion. This occurs due to the decreased adhesion sites between migrating epithelial cells as well as lack of adhesions to the basement membrane [decreased density of hemidesmosomes]. Recently the presence of a hyalinised membrane has been shown to further hinder adhesion of the epithelial layer. A thorough clinical investigation looking for foreign bodies, ectopic cilia or any eyelid abnormalities is essential. The treatment approach for these cases is to ensure there is no mechanical cause present [foreign body, cilia etc]. discomfort in the first 1-2 days. 3. Grid keratotomy - A grid keratotomy is performed by initially debriding the epithelium off the cornea with a blade and then creating a hatched, grid pattern across the entire erosion [using the bevel edge of a needle] through the basement membrane, which exposes epithelial cells to stromal collagen type I, which is believed to promote more effective basal cell attachment. A potential negative complication could be the extension or entrapment of infection into the superficial stroma. An equine soft contact lens can also be applied after this procedure and medicated as in [2] above. 4. Superficial keratectomy involves the complete removal of the basement membrane and anterior stroma and one relies on second intention healing. In all cases appropriate topical medications [antibiotics and atropine] and oral NSAIDs with or without a soft contact lens should be used. Corneal re-epitheliasation is expected to be about 0.6mm/day. The data showed that: The options include: 1. Mechanically debriding the sloughing edge with a cotton bud or more abrasive instrumentation. 2. Diamond head burr [Algerbrush] debridement which removes redundant epithelium in a controlled and uniform manner as well as the hyaline zone lining the base of the lesion. This is a newer treatment modality that has great potential as it can be performed under standing sedation, is relatively safe to perform and success rates are good. An equine contact lens and topical medication with Tobrex or Vigamox, Atropine drops and morphine drops can be added as an adjuvant preparation to assist in reducing Treatment method Healing time Debridement only 15.3 days Grid keratotomy 16 days Superficial Keratectomy 23 days % Success 63% 78-80% 78-80% Ref: Lassatine-Utter et al The data suggest that these surgical procedures are indicated but should only be performed following failure of the ulcer to heal after epithelial debridement References: Lassatine-Utter ML, Cutler TJ, Michau TM, Nunnery CM. Treatment of nonhealing corneal ulcers in 60 horses with diamond burr debridement (2010–2013). Vet Ophthalmol 2014;17 Suppl 1: 76–81. Michau T, Schwabenton B, Davidson M, et al. Su- perficial, nonhealing corneal ulcers in horses: 23 cases (1989–2003). Vet Ophthalmol 2003; 6:291–297. • Volume 20 Issue 1 | April 2018 • 49