Equine recurrent uveitis: A clinical manifestation of leptospirosis

Abstract

Summary Leptospirosis is a zoonosis of worldwide distribution affecting domestic animals, wildlife and man. The bacterial disease is caused by pathogenic Leptospira spp., which are transmitted from reservoir hosts to accidental hosts. Horses are accidental hosts and can become susceptible to leptospiral infections. Widespread exposure to leptospires exists and is significantly more common than clinical disease. Leptospirosis can have different clinical manifestations including abortion, still birth, systemic disease with hepatic or renal dysfunction, and equine recurrent uveitis (ERU). ERU is the most frequently encountered clinical manifestation and this article will focus on the review of leptospira‐associated ERU. Equine recurrent uveitis is the most common cause of vision impairment and blindness in horses. The pathogenesis of leptospira‐associated ERU involves direct bacterial effects and immune‐mediated responses. Clinical signs vary between the acute and chronic phases of the disease and progress over time. The diagnosis of leptospira‐associated ERU can be difficult and usually requires a combination of diagnostic tests. Medical and surgical treatments have been described with varying outcomes. The prognosis for sight is usually poor, although core vitrectomy may improve the outcome. Avoidance of leptospiral exposure of horses is the only reliable prevention of leptospira‐associated disease.

A retrospective histologic study of 140 cases of clinically significant equine ocular disorders

“…None of the cases had any reported history of ocular trauma. The ocular alterations accompanying keratitis consisted of anterior uveitis (22), corneal rupture (16) with secondary iris prolapse (9) and lens rupture (3), keratomalacia (13), pre-iridal fibrovascular membrane formation (13), hyphema (7), Descemet membrane rupture (5; Fig. 2), retinal detachment (4), mild panuveitis (3), cataract (3), and corneal stromal abscess (2).…”

“…Additionally, Appaloosas seem to be genetically predisposed. 10,13 The eosinophilic material that typically accumulates along the surface of the ciliary body in ERU cases and that is frequently referred to as “amyloid-like” 44 has been confirmed as amyloid, specifically as amyloid AA, in an ultrastructural and immunohistochemical study. 32 No infectious agents were identified within the globes affected by ERU in our study; however, some cases occurred concurrently with other diseases, such as sepsis (including R. equi infection), ocular neoplasms, and anterior segment dysgenesis.…”

A retrospective histologic study of 140 cases of clinically significant equine ocular disorders

“…None of the cases had any reported history of ocular trauma. The ocular alterations accompanying keratitis consisted of anterior uveitis (22), corneal rupture (16) with secondary iris prolapse (9) and lens rupture (3), keratomalacia (13), pre-iridal fibrovascular membrane formation (13), hyphema (7), Descemet membrane rupture (5; Fig. 2), retinal detachment (4), mild panuveitis (3), cataract (3), and corneal stromal abscess (2).…”

“…Additionally, Appaloosas seem to be genetically predisposed. 10,13 The eosinophilic material that typically accumulates along the surface of the ciliary body in ERU cases and that is frequently referred to as “amyloid-like” 44 has been confirmed as amyloid, specifically as amyloid AA, in an ultrastructural and immunohistochemical study. 32 No infectious agents were identified within the globes affected by ERU in our study; however, some cases occurred concurrently with other diseases, such as sepsis (including R. equi infection), ocular neoplasms, and anterior segment dysgenesis.…”

Equine uveitis: Outcome and adverse effects after one or two intravitreal low‐dose gentamicin injections

“…Pomona and L . Grippotyphosa are described as a common causative agent to ERU, 31 , 32 but these serovars were only prevalent in 0.4% and 0.5% respectively of the horses in the study by Baverud et al 34 From 2001 to 2021, 0–3 reported cases of seropositive horses were reported to the Swedish Board of Agriculture each year, and the prevalence of leptospirosis in Sweden is probably low. 35 Therefore, leptospiral testing has not previously been included in the standard protocol in the evaluation of Swedish horses with uveitis.…”

“…Leptospirosis is a well‐known inciting factor for chronic, persistent or recurrent uveitis. 12 , 30 , 31 , 32 The disease is endemic in many parts of the world, particularly in moist tropical and subtropical areas. 30 , 33 Baverud et al (2009) reported a seroprevalence of 25% in Swedish horses, but almost never related to clinical disease.…”

“…Leptospirosis is a well‐known inciting factor for chronic, persistent or recurrent uveitis 12,30–32 . The disease is endemic in many parts of the world, particularly in moist tropical and subtropical areas 30,33 .…”

A retrospective histologic study of 140 cases of clinically significant equine ocular disorders

“…None of the cases had any reported history of ocular trauma. The ocular alterations accompanying keratitis consisted of anterior uveitis (22), corneal rupture (16) with secondary iris prolapse (9) and lens rupture (3), keratomalacia (13), pre-iridal fibrovascular membrane formation (13), hyphema (7), Descemet membrane rupture (5; Fig. 2), retinal detachment (4), mild panuveitis (3), cataract (3), and corneal stromal abscess (2).…”

“…Additionally, Appaloosas seem to be genetically predisposed. 10,13 The eosinophilic material that typically accumulates along the surface of the ciliary body in ERU cases and that is frequently referred to as “amyloid-like” 44 has been confirmed as amyloid, specifically as amyloid AA, in an ultrastructural and immunohistochemical study. 32 No infectious agents were identified within the globes affected by ERU in our study; however, some cases occurred concurrently with other diseases, such as sepsis (including R. equi infection), ocular neoplasms, and anterior segment dysgenesis.…”

Equine uveitis: Outcome and adverse effects after one or two intravitreal low‐dose gentamicin injections

“…Pomona and L . Grippotyphosa are described as a common causative agent to ERU, 31 , 32 but these serovars were only prevalent in 0.4% and 0.5% respectively of the horses in the study by Baverud et al 34 From 2001 to 2021, 0–3 reported cases of seropositive horses were reported to the Swedish Board of Agriculture each year, and the prevalence of leptospirosis in Sweden is probably low. 35 Therefore, leptospiral testing has not previously been included in the standard protocol in the evaluation of Swedish horses with uveitis.…”

“…Leptospirosis is a well‐known inciting factor for chronic, persistent or recurrent uveitis. 12 , 30 , 31 , 32 The disease is endemic in many parts of the world, particularly in moist tropical and subtropical areas. 30 , 33 Baverud et al (2009) reported a seroprevalence of 25% in Swedish horses, but almost never related to clinical disease.…”

“…Leptospirosis is a well‐known inciting factor for chronic, persistent or recurrent uveitis 12,30–32 . The disease is endemic in many parts of the world, particularly in moist tropical and subtropical areas 30,33 .…”

A retrospective histologic study of 140 cases of clinically significant equine ocular disorders

“…None of the cases had any reported history of ocular trauma. The ocular alterations accompanying keratitis consisted of anterior uveitis (22), corneal rupture (16) with secondary iris prolapse (9) and lens rupture (3), keratomalacia (13), pre-iridal fibrovascular membrane formation (13), hyphema (7), Descemet membrane rupture (5; Fig. 2), retinal detachment (4), mild panuveitis (3), cataract (3), and corneal stromal abscess (2).…”

“…Additionally, Appaloosas seem to be genetically predisposed. 10,13 The eosinophilic material that typically accumulates along the surface of the ciliary body in ERU cases and that is frequently referred to as “amyloid-like” 44 has been confirmed as amyloid, specifically as amyloid AA, in an ultrastructural and immunohistochemical study. 32 No infectious agents were identified within the globes affected by ERU in our study; however, some cases occurred concurrently with other diseases, such as sepsis (including R. equi infection), ocular neoplasms, and anterior segment dysgenesis.…”

Equine uveitis: Outcome and adverse effects after one or two intravitreal low‐dose gentamicin injections

“…Pomona and L . Grippotyphosa are described as a common causative agent to ERU, 31 , 32 but these serovars were only prevalent in 0.4% and 0.5% respectively of the horses in the study by Baverud et al 34 From 2001 to 2021, 0–3 reported cases of seropositive horses were reported to the Swedish Board of Agriculture each year, and the prevalence of leptospirosis in Sweden is probably low. 35 Therefore, leptospiral testing has not previously been included in the standard protocol in the evaluation of Swedish horses with uveitis.…”

“…Leptospirosis is a well‐known inciting factor for chronic, persistent or recurrent uveitis. 12 , 30 , 31 , 32 The disease is endemic in many parts of the world, particularly in moist tropical and subtropical areas. 30 , 33 Baverud et al (2009) reported a seroprevalence of 25% in Swedish horses, but almost never related to clinical disease.…”

“…Leptospirosis is a well‐known inciting factor for chronic, persistent or recurrent uveitis 12,30–32 . The disease is endemic in many parts of the world, particularly in moist tropical and subtropical areas 30,33 .…”