Role of Leptospira spp. testing and ocular examination in horses with equine recurrent uveitis: A retrospective study of 63 horses

Summary Background There is little information on the correlation between equine recurrent uveitis (ERU) and leptospiral infection status as it relates to ocular examination findings and testing recommendations. Objective To evaluate the role of leptospiral testing in horses with ERU by correlating results to signalment, clinical findings and visual outcome. Study design Retrospective case series. Methods Records of horses presenting for ERU at NC State University Veterinary Health Complex (NCSU‐VHC) between 2014 and 2019 were reviewed. Signalment, initial visual status, ocular examination findings, treatments and visual outcome were collected. Serum and aqueous humour (AH) leptospiral titres were assessed for six different leptospirosis serovars and polymerase chain reaction (PCR) testing. Goldmann‐Whitmer (C) values were calculated. Results Records of 63 horses and 78 eyes with ERU were evaluated. Horses with a positive aqueous humour PCR were significantly younger in age (mean 9.25 ± 1.14) than PCR negative horses (mean 13.3 ± 0.95) (p = 0.01). A positive aqueous humour titre of any serotype was significantly correlated to blindness at presentation (p = 0.04). A positive serum titre was significantly correlated to presence of ocular posterior segment disease (p = 0.01). Positivity to L. bratislava in the serum correlated to posterior segment disease (p = 0.04) and AH positivity correlated to blindness at presentation (p = 0.002). Main limitations Limitations of this study include that it is a retrospective and information gathered relies on data included within medical records. Conclusions Positive leptospiral testing results were associated with younger horses and ocular posterior segment clinical disease. Horses with aqueous humour titres to any leptospiral serotype, especially L. bratislava serovar, were correlated to poor prognosis for vision.