LAUSR

BACKGROUND Quantifying risk factors for laminitis development requires improvement. OBJECTIVES To identify the most useful physical examination, metabolic and management factors to predict laminitis development in client-owned, non-laminitic ponies. STUDY DESIGN Prospective cohort study. METHODS Physical examination, metabolic and management data were collected from a pony cohort six-monthly for up to four years. Ponies were monitored for the development of laminitis. Metabolic data included basal plasma concentrations of ACTH ([ACTH]), adiponectin ([adiponectin]), triglycerides and glucose. Serum insulin concentrations ([insulin]) were measured in the unfasted basal state ([insulin]T0) and 60 minutes ([insulin]T60) after administration of corn syrup (0.3ml/kg). Separate multivariable Cox proportional-hazards models were developed for physical, management/ signalment and metabolic data and later combined into two final models. Low, medium and high laminitis risk categories were defined based on basal or T60 [insulin]. RESULTS 374 ponies (age 5-32 years) and 891 pony-years were included in the main analysis. Laminitis incidence (95% confidence interval (C.I.)) was 4.8 (3.5-6.5) cases/100 pony-years. Laminitis development was associated with numerous univariable factors. Significant (p<0.05) factors retained in the final multivariable models included [insulin]T0, [insulin]T60, [adiponectin] and divergent hoof growth. [ACTH] was not independently associated with laminitis. Based on [Insulin]T0, low (<21.6 µIU/ml), medium (21.6-45.2 µIU/ml) and high (>45.2 µIU/ml) risk categories encompassed 70, 20 and 10% of the population and had estimated 4-year laminitis incidences (95%CI) of 6 (2-9)%, 22 (10-33)% and 69 (48-82)% respectively. Based on [Insulin]T60 the low (<53.4 µIU/ml), medium (53.4-153 µIU/ml) and high (≥153 µIU/ml) risk categories comprised 60, 30 and 10% of the population and had estimated 4-year laminitis incidences (95%CI) of 3 (0-6)%, 20 (10-29)% and 73 (52-84)% respectively. MAIN LIMITATIONS Results may not apply to different insulin assays, geographic regions, breeds or management types. CONCLUSIONS [Insulin]T0 or [insulin]T60 best quantify the risk of future laminitis development in non-laminitic ponies.