Detection of Leptospira spp. in the aqueous humor of horses with naturally acquired recurrent uveitis.

Leptospiral organisms have long been presumed to be associated with the presence of equine recurrent uveitis. This project was undertaken to determine the presence of Leptospira spp. in the aqueous humor of horses with uveitis to determine if there was an association with inflammation. Thirty horses were determined to have recurrent uveitis based on clinical evaluation or history. Sixteen horses were judged clinically and historically to be free of uveitis and were used as controls. Aqueous humor samples were cultured and evaluated by PCR for the presence of Leptospira DNA. Serum was collected and evaluated for the presence of antibodies against five serovars in a leptospirosis panel. Twenty-one of 30 horses with recurrent uveitis and one of 16 uveitis-free horses were positive by PCR for the presence of Leptospira DNA. Six of these 21 horses with uveitis were culture positive for leptospires from the aqueous humor. Serologic results did not correlate well with the presence of Leptospira DNA or organisms in the aqueous humor. Leptospira spp. are present in a high percentage of horses with naturally occurring recurrent uveitis.