The effect of neonatal dysphagia on subsequent racing performance in Standardbred horses.

BACKGROUND: Previously we described a clustering of dysphagic foal cases on a Pennsylvania (PA) Standardbred farm which was associated with exposure of pregnant mares to high concentrations of polycyclic aromatic hydrocarbons (PAHs) in the well water. The effect of dysphagia on future athleticism was uncertain. OBJECTIVES: To determine if, as adults, dysphagic foals were less likely to race and if athleticism (age of first race, Speed Index and Earnings Per Start Index) differed from that of healthy foals that raced as adults. STUDY DESIGN: Prospective cohort study. METHODS: All foals born during the study period (2014-2017) on the affected PA or an unaffected New York (NY) farm with the same proprietor were eligible for inclusion in the study. Foals with dysphagia attributed to causes other than PAH environmental exposure were excluded. The proportion of foals from both farms that raced, their age of first race, Earnings Per Start Index and Speed Index were compared between the dysphagic and normal foals using Chi-Square and Wilcoxon Rank Sum Tests. Significance level was P < .05. RESULTS: A total of 116 foals met the inclusion criteria. No significant difference was found in the percentages of foals that raced from each farm: On the PA farm, 54% of healthy and 72% of dysphagic foals raced; 70% of healthy NY farm foals raced. Median (interquartile range) age of first race, Earnings Per Start Index or Speed Index for dysphagic foals (2 years (2, 2); 57 (49, 60); 60 (45, 66) was not different from those of healthy foals from both farms (2 years (2, 3); 55 (39, 78)) or the PA farm (2 years (2, 2); 61(24, 73); 68 (57, 85)). All P > .05. MAIN LIMITATIONS: Small sample size and unique type of dysphagia. CONCLUSIONS: The athleticism of formerly dysphagic foals does not appear to be negatively impacted compared with normal foals as measured by age of first race, Earnings Per Start Index and Speed Index.

The effect of strenuous exercise on mRNA concentrations of interleukin-12, interferon-gamma and interleukin-4 in equine pulmonary and peripheral blood mononuclear cells.

The effect of strenuous exercise on the mRNA concentrations of interleukin-12p35 subunit (IL-12p35), interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in equine pulmonary and peripheral blood mononuclear cells (PBMCs) was investigated. We hypothesized that strenuous exercise would suppress the expression of IL-12p35, IFN-gamma and augment the expression of IL-4. Eleven horses were randomly divided into two groups, a stall-confined control group (n=5) and an exercise-conditioned treatment group (n=6). Bronchoalveolar and PBMCs were obtained from horses in the treatment group prior to the commencement of a 9-week conditioning program and 24h after the completion of a maximum exercise test conducted in week 12. Samples were obtained simultaneously from control horses. Differential counts were performed on the bronchoalveolar lavage cells. Real-time PCR was performed on the pulmonary and PBMCs to quantitate cytokine expression using equine-specific primers and Taqman probes. Target gene expression was normalized to 18s rRNA expression. With the exception of IL-4 in the BALF cells, mRNA for the three cytokines was detected in the mononuclear cells from all horses at both sampling times. There were no significant differences in the cytokine mRNA concentrations between the two groups of horses at either of the sampling times. These findings demonstrate that strenuous treadmill exercise does not exert a deleterious effect on gene expression for IL-12p35, IFN-gamma or IL-4 when assessed in horses 24h following the intense physical activity.