Risk factors for equine recurrent uveitis in a population of Appaloosa horses in western Canada

Abstract

ObjectiveTo characterize clinical manifestations, measure frequency, and evaluate risk factors for equine recurrent uveitis (ERU) in Appaloosa horses in western Canada.Animals145 Appaloosa horses.ProceduresOphthalmic examinations were completed and eyes were classified as having no or mild clinical signs, or moderate, or severe damage from ERU. Clinical signs, age, sex, base coat color, and pattern were recorded. Whole blood and/or mane hair follicles were collected for DNA extraction, and all horses were tested for the leopard complex (LP) spotting pattern allele. Pedigree analysis was completed on affected and unaffected horses, and coefficients of coancestry (CC) and inbreeding (COI) were determined.ResultsEquine recurrent uveitis was confirmed in 20 (14%) horses. The mean age of affected horses was 12.3 years (±5.3; range 3‐25). Age was a significant risk factor for ERU diagnosis (ORyear = 1.15) and classification (ORyear = 1.19). The fewspot coat pattern was significantly associated with increased risk for ERU compared to horses that were minimally patterned or true solids. The LP/LP genotype was at a significantly greater risk for ERU compared to lp/lp (OR = 19.4) and LP/lp (OR = 6.37). Classification of ERU was greater in the LP/LP genotype compared to LP/lp. Affected horses had an average CC of 0.066, and there was a significant difference in the distribution of CC for affected horses versus the control group (P = .021). One affected horse was the sire or grandsire of nine other affected.ConclusionsAge, coat pattern, and genetics are major risk factors for the diagnosis and classification of ERU in the Appaloosa.

Detection of Anti-LipL32 Antibodies in Serum Samples from Horses with Chronic Intraocular Infection with Leptospira spp.

“…), Table S1: Results of MAT using equine Serum, Table S2: Results of SNAP Lepto using equine Serum, Table S3: Calculation of sensitivity, specificity, positive and negative predictive values (ppv and npv respectively) of MAT and SNAP Lepto using equine serum. References [120][121][122][123][124][125] are cited in the Supplementary Materials.…”

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis

“…As in other species, uveitis in horses can be caused by various etiologies. Equine recurrent uveitis (ERU) is the main form of uveitis occurrence worldwide, and is still the most common cause of blindness in equids [1][2][3][4][5][6][7][8]. The incidence of uveitis is 7-10% in Germany [9,10] and is reported to be 2-25% in the United States [5].…”

“…The term "ERU" is not used consistently in the literature. Many authors also refer to the chronic insidious uveitis of leopard coat pattern horses as "ERU" [5,7,13,14], whereas other publications distinguish between classic "ERU" and "leopard coat pattern uveitis", not only because of the ophthalmological findings and the course of the disease, but also because the etiology is different for each type of uveitis [15,16]. In horses suffering from recurrent episodes of typical uveitis attacks in central Europe, an intraocular leptospiral infection is almost always detectable [16][17][18][19][20][21].…”

“…Often, previous reports, the patient's signalement (e.g., age, breed, and coat color), the general examination (evidence of general disease, possible septicemia), and ophthalmologic examinations will indicate which form of uveitis is involved [22]. By far the most common types are equine recurrent uveitis (ERU) [1,5,7,11,12,15,16,[23][24][25][26][27][28][29] and "leopard coat pattern uveitis" [5,12,15,30]. Less commonly, possible etiologies include traumatic uveitis [5,18], phacogenic uveitis [18,31], chronic iritis (similar to human Fuchs' heterochromia iritis) [18,32], kerato-uveitis in severe corneal disease and co-reaction of the uvea [5], septicemia-accompanying uveitis [18,19,28,[33][34][35][36][37][38][39][40], uveitis induced by intraocular tumors [5], and endophthalmitis caused by pyogenic bacteria [5].…”

“…A genetic predisposition to uveitis has long been suspected [29,[49][50][51] and has further been investigated for both Appaloosas (belonging to leopard coat pattern horses) [1,7,[52][53][54] and warm-blooded horses [55,56]. Genetic factors predisposing to uveitis include immune system characteristics (e.g., the composition of major histocompatibility complexes (MHCs), immunocompetence with respect to defense against infectious agents, or favoring an autoaggressive response) as well as the anatomic configuration of the eye, particularly of the lens [3,5,18].…”