Recurrent Uveitis in Horses, New Insights

This article takes a big step forward in the pathogenesis, diagnosis, and treatment of Equine Recurrent Uveitis (EU):
1) The main cause of non-Appaloosa Recurrent Uveitis is a chronic leptospiral biofilm infection.
2) Diagnosis and differentiation from other causes of EU can be made with history, thorough ophthalmic exam, and antibody and/or PCR examination of the aqueous humor.
3) Lastly is the finding that a vitrectomy is often curative and preserves sight in the eye.
DrO

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis
Microorganisms. 2022 Feb 7;10(2):387. doi: 10.3390/microorganisms10020387.
Authors
Bettina Wollanke 1 , Hartmut Gerhards 1 , Kerstin Ackermann 1
Affiliation

1 Equine Clinic, Ludwig-Maximilians-University, 80539 Munich, Germany.

PMID: 35208842
DOI: 10.3390/microorganisms10020387

Abstract

Uveitis is a sight-threatening eye disease in equids known worldwide that leads to considerable pain and suffering. By far the most common type of uveitis in Germany and neighboring countries is classical equine recurrent uveitis (ERU), which is caused by chronic intraocular leptospiral infection and is the main cause of infectious uveitis in horses. Other infectious causes are extremely rare and are usually clinically distinguishable from ERU. ERU can be treated very effectively by vitreous cavity lavage (vitrectomy). For proper indications of this demanding surgery, it is necessary to differentiate ERU from other types of uveitis in which vitrectomy is not helpful. This can be conducted on the basis of anamnesis in combination with ophthalmologic findings and by aqueous humor examination. During vitrectomy, vitreous material is obtained. These vitreous samples have historically been used for numerous etiologic studies. In this way, a chronic intraocular leptospiral infection has been shown to be the cause of typical ERU and, among other findings, ERU has also been recognized as a biofilm infection, providing new insights into the pathogenesis of ERU and explaining some thus far unexplainable phenomena of ERU. ERU may not only have transmissible aspects to some types of uveitis in humans but may also serve as a model for a spontaneously occurring biofilm infection. Vitreous material obtained during therapeutically indicated vitrectomy can be used for further studies on in vivo biofilm formation, biofilm composition and possible therapeutic approaches.

Keywords: Goldmann–Witmer coefficient; Leptospira spp.; amyloid; aqueous and vitreous samples; biofilm infection; equine recurrent uveitis (ERU); local antibody production; neutrophil extracellular traps; vitrectomy.