Insulin dysregulation in a population of Finnhorses and associated phenotypic markers of obesity.

BACKGROUND

Obesity and insulin dysregulation (ID) predispose horses to laminitis. Determination of management practices or phenotypic markers associated with ID may benefit animal welfare.

OBJECTIVES

Determine ID status of a population of Finnhorses using an oral sugar test (OST) and compare phenotypes and management factors between ID and non-ID Finnhorses.

ANIMALS: One hundred twenty-eight purebred Finnhorses ≥3 years of age.

METHODS

Owners were recruited using an online questionnaire regarding signalment, history, feeding, and exercise of their horses. Selected contributing stables within a predefined area were visited. Phenotypic markers of obesity and the weight of each horse were recorded. After fasting overnight, horses received 0.45 mL/kg corn syrup PO. Serum samples before and at 60 and 90 minutes after syrup administration were analyzed for insulin by chemiluminescent assay. Horses met ID criteria if insulin concentrations were ≥33 μIU/mL at T0, ≥66 μIU/mL at T60 or T90 or some combination thereof. Associations between phenotypic markers, feeding and exercise variables, and ID were examined using mixed effects logistic regression modeling.

RESULTS

Several phenotypic markers of obesity were significant on univariable analysis but in the final multivariable model, only obesity (body condition score  ≥8) was associated with ID (P = .04). Over half of the horses (60% [95% confidence interval (CI), 51%-68%]) were considered overweight or obese whereas 16% (95% CI, 10%-23%) were classified as having ID.

CONCLUSIONS AND CLINICAL

IMPORTANCE

Because obesity is associated with ID in cold-blooded type horses, objective monitoring of phenotypic markers by owners may be beneficial for health outcomes.