Chronic intraocular leptospiral infection is the most common cause for recurrent uveitis in equids. History and a combination of typical ophthalmological findings can lead to suspected diagnosis of leptospiral induced uveitis. Testing intraocular fluids had been shown to be the most valuable tool for providing evidence of an intraocular leptospiral infection. The most appropriate treatment for recurrences of leptospiral uveitis is vitrectomy, whereas vitrectomy in non-leptospiral uveitis cases is less successful in regard of avoiding further damage to effected eyes. However, in cases in which clinical and ophthalmological findings are not typical for leptospiral induced uveitis, preoperative testing of aqueous fluid can be indicated to evaluate an indication for vitrectomy. Until now, for save sampling of aqueous humour, a general anaesthesia was necessary for paracentesis of the anterior chamber, and a second was necessary for vitrectomy in case of leptospira-positive laboratory results (either antibodies using microscopic agglutination tests (MAT), enzyme-linked immunosorbent assays (ELISA) or polymerase chain reactions (PCR) detecting LipL32). A quick ELISA test, the SNAP ® Lepto, has recently been made available to detect antibodies directed against LipL32 of pathogenic leptospires in any species. In order to evaluate the SNAP ® Lepto and to test whether it is effective with intraocular samples (aqueous and vitreous humour) from horses, 118 samples from equine eyes suffering from recurrent uveitis and 120 samples from equine control eyes were taken and tested with SNAP ® Lepto (detecting antibodies directed against LipL32), MAT (detecting antibodies directed against ten different serovars) and PCR (detecting the LipL32 antigen). If one of these tests was positive, an intraocular leptospiral infection was assumed.The result was that SNAP ® Lepto was positive in 114 out of 118 intraocular samples (97 %) from horses suffering from recurrent uveitis. SNAP ® Lepto was even superior to MAT, with a sensitivity of 0.97 (MAT 0.93). PCR was positive with fluids from eyes suffering from uveitis in 70 % of samples. There were no positive PCR results in any SNAP ® Lepto-negative samples from uveitic eyes and the MAT was positive in four SNAP ® Lepto-negative samples. On the other hand, SNAP ® Lepto gave a positive result in eight MAT-negative samples from eyes with uveitis. Furthermore, none of the antibody tests was positive regarding any sample from the control eyes, and PCR was positive in one single sample from a control eye. It can be concluded that SNAP ® Lepto, which gives a result within 10 minutes, is a valuable test method for detecting antibodies directed against LipL32 in intraocular fluids from horses. In the case of a negative result, MAT and PCR can be performed subsequently to reduce false negative results. Keywords: chronic intraocular leptospiral infection, equine recurrent uveitis (ERU), MAT, ELISA, serum, SNAP ® Lepto, anterior chamber fluid, vitreous Citation: Wollanke B., Geiger T., Gerhards H. (2018...