The outcome of pars plana vitrectomy in horses with equine recurrent uveitis with regard to the presence or absence of intravitreal antibodies against various serovars of Leptospira interrogans.

Abstract

Purpose: To evaluate the outcome of pars plana vitrectomy (PPV) in eyes with clinical signs of equine recurrent uveitis (ERU) testing positive or negative for intravitreal antibodies against various serovars of Leptospira interrogans. 47 eyes of horses with ERU in which intraoperative vitreous samples were tested by microagglutination (MAT) for various serovars of Leptospira interrogans between 2001 and 2009 were included in a retrospective study. The presence or absence of postoperative ERU was evaluated by repeated ocular examinations, as well as by interrogation of referring veterinarians and owners. The absence of recurrent episodes of active uveitis was considered a success irrespective of the visual performance of the operated eyes. 85% of eyes of horses with ERU had antibodies against L. interrogans in their vitreous. The most common serovar was L. grippothyphosa. The majority of horses testing positive for antibodies against L. interrogans (40/47; 82.5%) showed no further episodes of ERU, while 6/7 (85.7%) of horses testing negative continued to experience episodes of ERU. This difference is statistically significant. It appears that PPV is an effective treatment for Leptospira-associated ERU but not for eyes testing negative for antibodies against L. interrogans. Vitreal and aqueous humor samples of horses suffering from ERU should be tested by MAT before performing a PPV. Keywords: Equine recurrent uveitis, vitrectomy, Leptospira interrogans, antibodies, ophthalmology