2West Nile virus (WNV) mainly infects birds, horses and humans. Outcomes of the infection range from light uncharacteristic signs to fatal neurologic disease. The main objectives of the present study were to measure serum IgG and IgM antibodies in naturally exposed and vaccinated horses and to compare results of hemagglutination-inhibition test (HIT), enzymelinked immunosorbent assay (ELISA) and plaque reduction neutralization test (PRNT).Altogether 224 animals were tested with HIT for WNV antibodies and 41 horses were simultaneously examined with ELISA and PRNT. After primary screening for WNV antibodies, horses were vaccinated. Samples were taken immediately before and 3-5 weeks after each vaccination. McNemar chi-squared and percent agreement tests were used to detect concordance between HIT, ELISA and PRNT.Analyses by HIT confirmed the presence of WNV antibodies in 27/105 (25.71 %) from naturally exposed horses. Sera from 57/66 (86.36%) vaccinated animals were positive before the first booster and from 11/11 (100%) before the second booster. HIT was less sensitive when detecting IgG antibodies. We could detect post vaccination IgM in 13 cases with MAC-ELISA and in 7 cases with HIT.WNV is endemic in Hungary causing regular natural infections. Protective antibodies could not be measured in each individual case 12 months after primary injections; protection is more reliable after the first yearly booster. Based on our findings it was not be possible to differentiate infected horses from recently vaccinated horses using IgM antibody capture ELISA (MAC-ELISA). HIT does not substitute ELISA or PRNT when detecting IgG, but was useful tool in this study to gain statistical information about the tendencies within a fixed population of horses.
It is generally accepted that besides cortisol concentrations, parameters of heart rate variability (HRV) are appropriate indicators of stress in horses. The aim of this study was to determine anticipatory stress in eight Standardbred stallions participating in harness race. Cortisol and HRV responses to a mild exercise performed in training circumstances were compared to a maximal effort exercise performed in real trotting race conditions. Parameters of HRV reflecting vagal (root mean square of the successive differences, RMSSD) and sympathetic nervous system activity (ratio of the low and high frequency component, LF/HF) were recorded before warming up (baseline) and during exercise. Plasma cortisol concentrations were obtained for the following stages of the exercise: before warming up (baseline), after warming up, after the exercise has finished and after a 30-min recovery. Baseline LF/HF ratio was higher before the race compared to the pre-training values (12.0 ± 6.6 vs. 5.9 ± 4.5, P = 0.009), while RMSSD did not show such difference (34.8 ± 15.9 ms vs. 48.0 ± 30.5 ms, P = 0.96). Cortisol level was higher in the case of race for all samples compared to training (P = 0.012). There were no significant differences between plasma cortisol levels obtained for the subsequent stages of race. Horses in the present study showed anticipatory response before race as shown by differences in pre-training (97.3 ± 16.4 nmol/L) and pre-race cortisol levels (171.8 ± 18.7 nmol/L), respectively (P < 0.001). Pre-race HRV only partly confirmed this phenomenon.
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