Relationships between total adiponectin concentrations and obesity in native‐breed ponies in England

Abstract

AbstractBackgroundEquine metabolic syndrome is a collection of risk factors associated with an increased risk of endocrinopathic laminitis. All affected animals display insulin dysregulation and some may show adiponectin dysregulation and/or excessive adiposity. However, the relationship between obesity and hypoadiponectinaemia in equids remains unclear.ObjectivesTo investigate the relationship between obesity and circulating plasma total adiponectin (TA) concentrations in native‐breed ponies in England.Study designSecondary data analysis.MethodsData collected for three previous studies were retrospectively analysed and cohorts were pooled where possible (maximum sample size: n = 734 ponies). Correlations between [TA], age, and morphometric measures were assessed using Spearman's correlation coefficient. [TA] was compared between animals of different body condition score (BCS) classification (ideal‐weight, overweight, and obese), breed, and body shape using Kruskal–Wallis with Dunn's post hoc tests, and sex using Mann–Whitney U test. The proportions of obese and ideal‐weight ponies with basal hyperinsulinaemia and/or hypoadiponectinaemia were compared using a Chi‐square test of homogeneity and post hoc z‐test. Logistic regression was used to identify factors that may discriminate ponies with hypoadiponectinaemia.Results[TA] was weakly positively correlated with BCS, height, weight, and weight:height ratio (Spearman's ρ = 0.14–0.29, p < 0.05). There were significant differences in [TA] in ponies with different BCS group classification, body shape, and breed. A greater percentage of obese (54.6%) than ideal‐weight ponies (33.1%, p < 0.001) had both normal [TA] and [basal insulin], and a greater percentage of ideal‐weight (38.6%) than obese ponies (16.5%, p < 0.001) showed hypoadiponectinaemia. Weight:height and BCS group were significant variables in a logistic regression of hypoadiponectinaemia but model fit and predictive accuracy were poor.Main limitationsRetrospective study design, only native‐breed ponies included.ConclusionsMorphometric measures such as BCS do not closely reflect [TA]. Circulating [TA] and [basal insulin] should be determined in all animals with predisposing factors, regardless of obesity status.