Nonulcerative keratouveitis as a manifestation of Leptospiral infection in a horse

Abstract

A 2-year-old Thoroughbred filly presented with ocular pain and epiphora of the left eye. The pupil was miotic and the cornea edematous near the ventro-temporal limbus, but did not retain any fluorescein. The topical antibiotics and atropine and diclofenac, and systemic flunixin meglumine and antibiotic therapy did not resolve the condition. A pink and fleshy infiltrate developed near the limbus indicating nonulcerative keratouveitis. The anterior uveitis deteriorated as manifested by the presence of dyscoria, hypopyon, and organized fibrin in the anterior chamber. Ocular signs were improved by topical and subconjunctival corticosteroids, but repeatedly deteriorated as the frequency of medication was reduced. The horse was seropositive to three serovars of Leptospira interrogans. The animal was diagnosed as blind on day 91 by the absence of pupillary light and menace reflexes, and donated for histopathologic diagnosis. The corneal opacity was histologically fibrotic and infiltrated predominantly by lymphocytes with Descemet's membrane partially disrupted by macrophages. The choroid was infiltrated by lymphocytes, eosinophils and basophils, and was positive to IgG and C3. There were filamentous or spiral structures positive to Warthin-Starry stain in the renal cortex. There was also polymerase chain reaction amplification of the leptospiral gene in the kidney. From these findings nonulcerative keratouveitis was believed to be caused by systemic infection with Leptospira.

Immune‐mediated keratitis in horses: 19 cases (1998–2004)

“…with loss of corneal epithelium) keratitis is commonly caused by trauma, and delayed healing of corneal lesions is frequently associated with development of secondary infections 1,5,7,8,10–13 . Nonulcerative keratopathies in horses are characterized as chronic corneal lesions with cellular infiltrate, vascularization, and variable degrees of ocular discomfort 2,3,5,6,9,14–18 . Causes of nonulcerative keratitis in the horse include onchocerciasis, 19,20 bacterial infections, 1 fungal infections, 7,8,10–13,21–23 infiltrative neoplasia, 24,25 corneal degeneration 9 and immune‐mediated inflammation 3,9,15,16,26 .…”

Changes of Intraocular Pressure in Uveitic Horses

“…Although retinal detachment was not observed in case 2 during the treatment period of 3 weeks, it was possible that the detachment would develop after the animal was lost to follow up as the decrease in IOP was remarkable and the fundic lesion progressive. Retinal detachment has been reported histopathologically also in a horse with chronic NKU [25]. From remarkably decreased IOPs of case 5, the author considers hypotony could partially explain retinal detachment in NKU horses.…”

“…Increased availability of applanation tonometers has made it easier to measure IOP in equine practice to diagnose and to select and/or determine the effect of re g im en of th er ap y for gl a ucoma [3,6,25 ]. Applanation tonometry is also performed to evaluate effects of drugs on IOP in horses [14, 15, 21-24, 28, 29].…”

“…On day 16, IOP was 6 (OS) and 11.3 mmHg (OD) and topical dexamethasone was reduced to BID. The corneal lesion was smaller and less vascularized although it was opaque in the innermost part probably with a layer of fibroblasts [25]. IOP on day 23 was 10.7 OS and 17.3 mmHg OD.…”

Clinical experience and long-term outcome after subscleral insertion of a cyclosporine A drug delivery device in horses with immune-mediated keratitis

“…Yet, the results of the study at hand indicate a certain effect against IMMK. This could be based upon the fact that IMMK is thought to be not solely a disease of the cornea but rather a type of anterior uveitis (Parma et al 1985, Parma et al 1987, Holland et al 1993, Lucchesi and Parma 1999, Lucchesi et al 2002, Wada et al 2003. It might also explain why topically applied eye ointment does not reliably control IMMK as it does not diffuse into the deeper layers but instead only affects the superficial tissues (Bleik and Tabbara 1991, Sec-J.…”