Equine recurrent uveitis (Proceedings)


Equine recurrent uveitis (Proceedings)

Aug 01, 2011

Herpes virus keratitis

     • Prevalence:
          o EHV-2 has a high overall seropositive rate (90%) that does not have a defined correlation with clinical disease
          o Affects foals and adults
     • Clinical Appearance:
          o Variable pain, blepharospasm, epiphora, edema, vascularization
          o Common: classic appearance of multiple multifocal opacities which may be rose bengal positive (superficial erosion) or fluorescein stain positive (superficial ulcer); does not have to have stain retention
          o EHV-1 manifestations (blindness, optic neuritis, strabismus) distinctly different
     • DDX:
          o Influenced by region
          o Immune-mediated - Midwest
          o Early fungal – primary differential for many
          o Other ulcerative – traumatic, foreign body, KCS
          o Non-ulcerative keratitis – immune-mediated keratitis, corneal degeneration, calcific band keratopathy
          o Conformation difficult – high seropositive in normal population
          o Primarily – Rule out diagnosis combined with positive response to tx
          o Electron microscopy, virus isolation,
     • Pathogenesis:
          o EHV-2 is a gamma herpesvirus producing lifelong infections characterized by variable periods of disease recrudescence and latency.
          o Reactivation associated with stress (shipping, training, breeding)
          o Latency established in lymphocytes and trigeminal and ciliary ganglia
     • TX:
          o Anti-viral efficacy for equine EHV-2 have not been tested in vivo or in vitro
          o Anti-viral medications considered virostatic and must be administered at high frequency (4-6 times daily)
          o Topical NSAID
          o Topical prophylactic antibacterial
          o Systemic NSAID
          o Lysine – 10-30 grams orally once daily
          o Topical cycloplegic – mydriatic for reflex keratouveitis
          o Topical steroid?
     • Prognosis: Variable, often taking time and patience

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