Leptospiral antibody prevalence and surgical treatment outcome in horses with Equine Recurrent Uveitis (ERU) in Switzerland.

OBJECTIVE: To evaluate leptospiral antibody prevalence in 65 horses with ERU and compare outcome in 36 surgically treated eyes (2010-2015). PROCEDURES: Retrospective data analysis of horses with ERU (n = 65). C-value calculation with microagglutination assay titer (MAT) results for Leptospira spp. Evaluation of follow-up data after pars plana vitrectomy (PPV, n = 21 eyes) and suprachoroidal cyclosporine device implantation (SCDI, n = 15 eyes). Differences between groups were statistically analyzed using Fishers exact test, significance set at P < .05. RESULTS: Positive leptospiral titers were found in 28/65 blood, 31/65 aqueous humor (AH), and 19/20 vitreal (post-PPV) samples. The most common intraocular serovars were Leptospira interrogans grippotyphosa, pomona, and bratislava. Intraocular antibody production was suspected in samples of 22 horses (c-values > 1). Mean follow-up of surgical cases was 3.8 years (PPV) and 3.4 years (SCDI). PPV was performed in 21 eyes with positive, SCDI in 15 eyes with negative leptospiral test results. Uveitis recurred less often after PPV (2/21) compared to SCDI (6/15, P = .04). Retinal detachment occurred after PPV only (5/21, SCDI 0/15, P = .06), whereas only SCDI-treated eyes were enucleated (PPV 0/21, SCDI 3/15, P = .06). Blindness or visual impairment was equally likely to occur in both treatment groups after surgery (PPV 7/21, SCDI 7/15, P = .5). CONCLUSIONS: Leptospiral antibody prevalence is high in horses with ERU in Switzerland. Recurrence of uveitis is uncommon following PPV in the present study; an increased risk of retinal detachment exists. Enucleation is more often warranted in horses after SCDI in this study due to a higher uveitis recurrence.

Aquaporin 11, a regulator of water efflux at retinal Müller glial cell surface decreases concomitant with immune-mediated gliosis.

BACKGROUND: Müller glial cells are important regulators of physiological function of retina. In a model disease of retinal inflammation and spontaneous recurrent uveitis in horses (ERU), we could show that retinal Müller glial cells significantly change potassium and water channel protein expression during autoimmune pathogenesis. The most significantly changed channel protein in neuroinflammatory ERU was aquaporin 11 (AQP11). Aquaporins (AQP, 13 members) are important regulators of water and small solute transport through membranes. AQP11 is an unorthodox member of this family and was assigned to a third group of AQPs because of its difference in amino acid sequence (conserved sequence is only 11 %) and especially its largely unknown function. METHODS: In order to gain insight into the distribution, localization, and function of AQP11 in the retina, we first developed a novel monoclonal antibody for AQP11 enabling quantification, localization, and functional studies. RESULTS: In the horse retina, AQP11 was exclusively expressed at Müller glial cell membranes. In uveitic condition, AQP11 disappeared from gliotic Müller cells concomitant with glutamine synthase. Since function of AQP11 is still under debate, we assessed the impact of AQP11 channel on cell volume regulation of primary Müller glial cells under different osmotic conditions. We conclude a concomitant role for AQP11 with AQP4 in water efflux from these glial cells, which is disturbed in ERU. This could probably contribute to swelling and subsequent severe complication of retinal edema through impaired intracellular fluid regulation. CONCLUSIONS: Therefore, AQP11 is important for physiological Müller glia function and the expression pattern and function of this water channel seems to have distinct functions in central nervous system. The significant reduction in neuroinflammation points to a crucial role in pathogenesis of autoimmune uveitis.

Examination techniques and therapeutic regimens for the ruminant and camelid eye.

A step-wise procedure and necessary equipment for examination of the ruminant and camelid eye are detailed. Restraint techniques and usage of local anesthetics to facilitate examination are described. Common examination findings and their significance are discussed. Finally, therapeutic options for keratoconjunctivitis and uveitis are explored. A complete ocular examination of ruminants is often not performed in the field because of lack of time, lack of appropriate facilities, and/or lack of equipment. Although individual ophthalmic examinations are not frequently performed as part of a herd health program, they can be of value in select cases. Ocular manifestations of systemic diseases may assist the clinician in establishing a diagnosis on the farm and for little additional cost. For patients with a specific ocular complaint, a complete ophthalmic examination is critical. After completion of the examination and arrival at a diagnosis, one must also be cognizant of the therapeutic regimens that are appropriate for use in ruminants, particularly animals that may be used for meat or milk.

Diagnosis and treatment of ocular coccidioidomycosis in a female captive chimpanzee (Pan troglodytes): a case study.

We report here the first documented case of ocular coccidioidomycosis in a chimpanzee (Pan troglodytes). In 1996, a 12-year-old female chimpanzee was undergoing treatment with an experimental triazole, BayR3783, for coccidioidomycosis when she was diagnosed with severe conjunctivitis in the right eye. Subsequent development of a coccidioidal granuloma of the ventral conjunctiva and anterior uvea was noted over the next several months, distorting the lens, iris, pupil, and sclera and progressing to uveitis. Treatment with BayR3783 and subconjunctival injections of triamcinolone were successful in reducing the ocular mass, but extensive damage was done to the lens and cornea. This case study provides an interesting comparison to ocular coccidioidomycosis cases observed in both humans and canines.

The uveitogenic potential of retinal S-antigen in horses.

PURPOSE: To investigate the uveitogenic potential of retinal S-antigen (S-Ag) in horses. METHODS: Horses were immunized subcutaneously with S-Ag or BSA as control antigen, emulsified in complete Freund's adjuvant. Simultaneously, Bordetella pertussis was given intravenously. Antigen specific T- and B-cell responses were analyzed in a 3-day interval. Disease development was judged clinically and histopathologically. Two identical booster immunizations were given every 4 weeks to test induction of recurrences. RESULTS: T- and B-cell responses specific for S-Ag were observed in all immunized horses but were absent in control animals. However, uveitis developed in only one of five animals. Reimmunization with S-Ag did not lead to a uveitic relapse in this horse. All other horses of the S-Ag- and BSA-treated groups neither showed any signs of uveitis, nor had inflammatory infiltrates of the inner eye. CONCLUSIONS: In contrast to interphotoreceptor retinoid-binding protein (IRBP), S-Ag is a weak autoantigen in horses. Even though S-Ag immunization leads to the activation of autoreactive T- and B-cells, infiltration of the inner eye and induction of uveitis are controlled in most horses.

Uveitis in horses induced by interphotoreceptor retinoid-binding protein is similar to the spontaneous disease.

Equine recurrent uveitis (ERU) is an inflammatory eye disease with high similarity to uveitis in man. It is the only spontaneous animal model for uveitis and the most frequent eye disease in horses affecting up to 10% of the population. To further investigate the pathophysiology of ERU we now report the establishment of an inducible uveitis model in horses. An ERU-like disease was elicited in seven out of seven horses by injection of interphotoreceptor retinoid-binding protein (IRBP) in complete Freund's adjuvant. Control horses did not develop uveitis. The disease model is characterized by a highly reproducible disease course and recurrent episodes with an identical time course elicited in all horses by repeated IRBP injections. The histology revealed the formation of lymphoid follicle-like structures in the eyes and an intraocular infiltration dominated by CD3(+) lymphocytes, morphological patterns typical for the spontaneous disease. Antigen-specific T cell proliferation of PBL was monitored prior to clinical uveitis and during disease episodes. An initial T cell response to IRBP-derived peptides was followed by epitope spreading to S-antigen-derived peptides in response to subsequent immunizations. Thus, horse experimental uveitis represents a valuable disease model for comparative studies with the spontaneous disease and the investigation of immunomodulatory therapeutic approaches after onset of the disease.

Ocular Halicephalobus (syn. Micronema) deletrix in a horse.

Ocular contents from a horse with a 4-week history of severe unilateral uveitis were submitted for histopathologic examination. A severe unilateral granulomatous chorioretinitis with intralesional Halicephalobus deletrix was diagnosed. The horse developed progressive neurologic signs several days following the surgery to remove ocular contents and implant a prosthesis and was subsequently euthanatized. A severe multifocal granulomatous encephalitis with intralesional H. deletrix, localized primarily to the optic chiasm, thalamus, and brain stem, was diagnosed from tissues acquired at necropsy. The other eye was not affected. This is the first report of ocular parasitism by H. deletrix and suggests possible systemic dissemination from a primary site in the eye.