2018 ACVIM Forum Research Abstract Program: Seattle, Washington, June 14 - 15, 2018

Combination of the TRH stimulation test and the 2-step insulin sensitivity test appears as an attractive and rapid tool to diagnose EMS and PPID at the same time in horses. the curve (AUC) and peak concentrations for insulin and glucose were assessed using a one-way ANOVA (significant at P < 0.05). Repeatability was assessed using Bland-Altman Plots. Significant differences were not noted between KLCS and FCS for either AUC or peak concentrations. However, when insulin results were compared to the ID positive insulin cut off, tests with fructose correctly identified horses with ID only 8 of 14 times; OSTs without fructose identified ID in 12 of the 14 tests. Based on this, fructose does not have a substantial impact on glucose metabolism in horses, but may interfere with insulin responses during an OST. Vitamin E is essential for neuromuscular function. Oral supplementation with natural ("RRR") α-tocopherol has been the mainstay of therapy in horses with hypovitaminosis E. However, there is a subset of non-responsive horses. The objectives of this pilot trial were to evaluate the safety and efficacy of an injectable RRR-α-tocopherol preparation delivered subcutaneously. We hypothesized that RRRα-tocopherol injection would increase serum and cerebrospinal fluid (CSF) α-tocopherol concentrations in healthy adult horses. Six mixed breed horses (3 mares and 3 geldings) and two untreated horses (1 mare and 1 gelding) were enrolled. In Phase I, horses were randomly assigned to receive RRR-α-tocopherol (5000 IU/450kg of 600 IU/mL) by subcutaneous (n=3) or oral (n=3) administration. Moderate tissue reaction following injection necessitated adjustment of the preparation through reduction of the RRR-α-tocopherol concentration to 500 IU/mL. Following an 8-week washout period, horses received the reciprocal treatment in Phase II with the new preparation at an equivalent dose. Alpha-tocopherol concentrations of serum and CSF collected over a 7d period were determined by HPLC. There was no difference in baseline serum (P=0.07) or CSF (P=0.20) concentrations and no residual effect noted, indicating appropriate washout. Serum (P < 0.0001) and CSF (P=0.0.007) α-tocopherol concentrations increased significantly post-injection only when the 500 IU/mL product was administered, with serum concentrations peaking at 24h post-injection. This injectable formulation may therefore be useful in cases refractory to oral supplementation. However, caution is warranted due to the marked local tissue reaction observed in all horses. Hypophosphatemia, hypokalemia, and hypomagnesemia are associated with various diseases in equids. Despite the interactions between these analytes and energy metabolism, evaluation of their concentrations in critically ill equids with lipid disorders is not frequently performed; therefore, the incidence of these abnormalities in these patients remains unclear. Medical records from 54 hospitalized small equids [ponies (multiple breeds), American Miniature Horses, and donkeys] greater than 2 years of age with serum triglyceride concentrations greater than 200 mg/dL admitted between 2002-2017 were reviewed, and relationships between biochemical analytes were assessed (Chi-square analysis).