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Frontiers in veterinary science2025; 11; 1504990; doi: 10.3389/fvets.2024.1504990

Uveitis and blindness in a closed herd of Equidae following leptospiral infection.

Abstract: To describe the ocular findings, chronology of disease, and serum leptospiral titers in a group of horses, mules, and donkeys following an outbreak of leptospirosis. Unassigned: Fifty Equidae in central North Carolina had ophthalmic examinations and serum leptospiral microscopic agglutination test (MAT) titers performed every 3-6 months for 24 months followed by a final examination at 34 months. Unassigned: Throughout the nearly three-year study period, 17 horses (34%; 17/49 horses) developed signs of uveitis; 20 eyes (20/34; 58.8%) of these 17 horses were visual at the initial examination, but only four eyes (11.8%) remained visual at the final examination. Serum titers (serogroups Pomona and Bratislava) in horses with uveitis were significantly elevated compared to Equidae without uveitis (p < 0.02). In the 32 horses, donkeys, and mules that did not develop uveitis, a subgroup of 11 horses and one donkey had negative or low serum leptospiral titers (titers ≤1:800) while a second subgroup of 16 horses, three mules, and one donkey had high leptospiral titers (>1:800) but never developed uveitis. Water sources in the pasture were found to have high levels of leptospira. Unassigned: Approximately 1/3 of horses on a farm exposed to Leptospira developed uveitis and blindness. Serum titers to L. Pomona and L. Bratislava were significantly elevated in horses with uveitis. However, despite exposure, some horses, even with very high serum titers, never developed ocular disease. These data indicates that further research is warranted to investigate the genetic and immunological aspects of the pathogenesis and susceptibility of leptospiral-associated uveitis.
Publication Date: 2025-01-06 PubMed ID: 39834922PubMed Central: PMC11743373DOI: 10.3389/fvets.2024.1504990Google Scholar: Lookup
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  • Journal Article

Summary

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This research study investigated the connection between an outbreak of the bacterial infection leptospirosis in a group of horses, mules, and donkeys and the development of uveitis and blindness. The study found that about a third of the equines developed uveitis and significant vision loss, with serum titers for leptospira distinctly elevated in affected individuals.

Demographic and Epidemiological Data

  • The study involved 50 horses, mules, and donkeys in North Carolina that were regularly tested over a period of approximately three years.
  • About 34% of the horses developed signs of uveitis (inflammation of the middle eye layer) during the study, with significant vision loss observed in many of these cases. Initially, 58.8% of these eyes were normal, but by the end of the study, only 11.8% remained so.

Correlation between Uveitis and Leptospiral Titers

  • In horses that developed uveitis, serum leptospiral titers, particularly for the serogroups Pomona and Bratislava, were significantly elevated compared to those without the disease, suggesting a possible link between leptospirosis and the development of uveitis.
  • Despite this, not all horses with high leptospiral titers developed uveitis. The horses, donkeys, and mules were divided into subgroups based on serum leptospiral titers. One subgroup with low titers did not develop uveitis, and even in a subgroup with high titers, no uveitis developed. This could suggest a possible genetic or immune component to susceptibility.

Risk Factors

  • Water sources in the horses’ pasture were found to have high levels of leptospira, which may have been a potential source of exposure and subsequent infection.
  • About one-third of horses exposed to leptospira developed uveitis and blindness, further underscoring the link between leptospira exposure and disease development.

Implications and Further Research

  • The findings highlight the need for additional research on the genetic and immunological aspects of the development and progression of leptospiral-associated uveitis. Understanding these aspects can help in the development of preventive and treatment strategies.

Cite This Article

APA
Gerras J, Young K, Roberts D, Waldman G, Salmon JH, Gilger BC. (2025). Uveitis and blindness in a closed herd of Equidae following leptospiral infection. Front Vet Sci, 11, 1504990. https://doi.org/10.3389/fvets.2024.1504990

Publication

ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 11
Pages: 1504990

Researcher Affiliations

Gerras, J
  • Department of Clinical Sciences, North Carolina State University, Raleigh, NC, United States.
Young, K
  • Department of Clinical Sciences, North Carolina State University, Raleigh, NC, United States.
Roberts, D
  • Department of Clinical Sciences, North Carolina State University, Raleigh, NC, United States.
Waldman, G
  • Rivendell Mobile Large Animal, Advance, NC, United States.
Salmon, J H
  • Department of Clinical Sciences, North Carolina State University, Raleigh, NC, United States.
Gilger, B C
  • Department of Clinical Sciences, North Carolina State University, Raleigh, NC, United States.

Grant Funding

  • T35 OD011070 / NIH HHS

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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