2017 ACVIM Forum Research Abstract Program

We have previously reported the measurement of the concentration of EDCs capable of activating the aryl hydrocarbon receptor via a bioassay (AHR-EDC); and the correlations between these EDCs and metabolic measurements in 301 horses from 32 farms. Here we extend these findings by presenting correlations between EDCs capable of activating the estrogen receptor (ER-EDC). Significance was P < 0.05. Mean (range) ER-EDC concentrations were 279.66 (4.35-15,000) pg/mL plasma. EDCs were below the detection limit in approximately half of the horses. AICc statistics were used to determine the best linear multivariable regression model for EDC association with 9 EMS phenotypic variables. ER-EDC was associated with glucose after an oral sugar test (OST), glucose, insulin and insulin-OST. Overall, these results suggest that some of the unexplained environmental variance in individuals with EMS is due to EDC exposure, which is mediated in part through the estrogen and arylhydrocarbon receptors. Pituitary Pars Intermedia Dysfunction (PPID) has been described as one of the most common diseases of horses and ponies 15 years of age and older. Recently, the clinical signs of PPID have been divided into early and advanced clinical signs. Establishing a diagnosis of PPID in horses with early clinical signs is currently a difficult challenge facing equine veterinarians. Particularly difficult may be the diagnosis of horses with PPID in the equine athlete. Many of the same clinical signs identified in early or advanced PPID may be recognized in the sport horse along with tendon or suspensory ligament degeneration. Suspensory ligament injuries have been considered a common cause of lameness, in the equine athlete involved in competitive events. A recent histopathological study concluded that an association exists between PPID and suspensory ligament (SL) degeneration. The objective of this study was to identify the most common clinical signs associated with PPID in the sport horse. Sport horses >10 years of age, any breed, and sex were eligible for study enrollment as long as they were documented to be exhibiting one or more of the early or advanced clinical signs of PPID including suspensory ligament desmitis. Forty-nine horses were evaluated and included in the final data analysis with at least one clinical sign of early or advanced PPID. Demographic data, signalment, and a physical examination was conducted and each horse was tested for PPID using the TRH stimulation test measuring ACTH at 0 (T0ACTH) and 10 (T10ACTH) min. Insulin and glucose levels were also determined. Normal horses were excluded from the study. Blood samples were shipped overnight to the Animal Health Diagnostic Center, Cornell University, Ithaca, NY for analysis. The association between PPID status, based on ACTH and insulin results, and each of the demographic variables (age, sex, and breed), clinical signs, the two test result variables insulin and glucose were statistically evaluated individually using the Pearson chi-square test. Odds ratios for significant predictors of PPID status were computed using corresponding 95% confidence intervals when applying multiple logistic regression analysis.