EXPRESS: Evaluation of Leptospira spp. as a cause of endogenous uveitis in cats: A pilot study

Objectives: While Leptospira spp. infections can be associated with intraocular inflammation in dogs and horses, there is limited information regarding the role these agents play in feline uveitis. The primary objective of this study was to report the prevalence of Leptospira spp. antibodies and DNA in samples from cats with endogenous uveitis. The secondary objective was to assess for co-infections by Bartonella spp., Toxoplasma gondii, and eubacteria. Methods: Serum and aqueous humor (AH) from 37 cats diagnosed with endogenous uveitis that had been stored at -80°C were selected for this study based on sample availability. Polymerase chain reaction (PCR) assays for Leptospira spp., T. gondii, Bartonella spp., and 16S eubacterial DNA were performed on AH. Sera were evaluated for antibodies against Leptospira spp. (microscopic agglutination test; MAT), Bartonella spp. (IgG ELISA), and T. gondii (IgM and IgG ELISA). Results: While sera from two cats (5.4%; 2/37) were positive for antibodies against Leptospira interrogans serovar pomona by MAT (1:100 titers), all AH samples were negative for DNA of Leptospira spp. One AH sample was positive for DNA of a Streptococcus spp. but all were negative for DNA of T. gondii and Bartonella spp. Serum antibodies against Bartonella spp. (56.8%; 21/37), T. gondii (18.9%; 7/37), or multiple agents (13.5%; 5/37) were common. Conclusions and relevance: While results of this study cannot be used to prove or deny Leptospira spp. as a cause of endogenous uveitis in cats, the detection of specific antibodies against Leptospira interrogans serovar pomona in the sera of two cats suggests that a larger cohort of cats should be tested to further evaluate the hypothesis. One cat had AH positive DNA for a Streptococcus spp. and future studies should investigate if post-Streptococcus uveitis syndrome also can be found in cats.