2016 ACVIM Forum Research Abstract Program

Different from what is currently recommended in the literature, we advise measuring the insulin concentration of a single blood sample at 60, 75, 90, or 120 minutes post-Karo syrup administration and using a ≥ 30.2 IU/mL threshold. Practitioners should be aware that breed may play a role in insulin concentrations that are achieved during the OST. Values >20 µU/mL after overnight fasting and >50 µU/mL in hay fed horses are considered supportive of insulin dysregulation. Although it is well recognized that INS increases with body condition (fat mass), recent evidence suggests that there may also be age and breed differences with regard to basal insulin concentrations. However, little data exists for draft breeds. Consequently, we tested the hypothesis that INS differs in various breeds of draft horses, independent of age and body condition. Age was obtained from owners/trainers and body condition score (BCS) was assessed and basal (resting but not fasting) INS was measured in 164 draft horses participating in an international competition, including 48 Belgians, 52 Clydesdales, and 64 Percherons. INS was measured using a radioimmunoassay validated for equine serum (with average intra-and inter-assays CVs of 3.4% & 6.9% and 4.7% & 7.2% for low and high equine control sera, respectively). None of the horses examined had a history or current evidence of laminitis. Age, BCS, and INS were not normally distributed; thus, median values and 25% and 75% confidence intervals were determined (Table) . Data were analyzed using ANOVA on ranks, Chi square analysis, and Spearman rank order correlation.