Evaluation of risk factors affecting strongylid egg shedding on Hungarian horse farms.

In Hungary, equine parasite control is mostly based on traditional approaches involving rotational anthelmintic treatment at regular intervals. Almost no farms utilize fecal egg counts (FECs) on a regular basis to guide deworming treatments. This approach is certainly not sustainable and is the major factor responsible for the current high levels of anthelmintic resistance. The aims of this study were to statistically analyze risk factors associated with strongylid egg count magnitude and prevalence. Fecal samples and horse data (age, pasture history, stocking density, anthelmintic history) were collected from 216 horses on 13 farms in Pest county, Hungary, during the spring of 2020. FECs were determined by Mini-FLOTAC. Logistic regression models were used to evaluate the association of factors with pre-deworming strongylid egg counts. The data were highly overdispersed with approximately 22% (95% Confidence Interval: 17-28%) of the equids shedding 80% of the total strongylid egg output. Strongylid FECs were significantly associated with the age of equids and anthelmintic class used prior to the study. Equids younger than 5 years of age had significantly higher FECs compared to equids in the 5-17-year age range (p = 0.003) and compared to equids aged >17 years (p < 0.001). Equids treated regularly with benzimidazoles had significantly higher FECs than equids with no history of benzimidazole use (p = 0.02). We found that FECs of horses kept at extremely high stocking density (>30 horses/ha) were significantly higher than those kept at low (1-2 horses/ha; p < 0.001) or medium (3-10 horses/ha, p < 0.001) stocking densities. The results demonstrate the value of FEC monitoring and indicate that the efficacy of benzimidazoles should be investigated in Hungary. Moreover our findings demonstrate that reducing stocking density should be considered in cases of high strongylid FECs.

Evaluation of Overground Endoscopy Findings in Colombian Criollo Paso Horses.

The dynamic upper airway functional (URT) problems of Colombian paso horses (CPH) have not been investigated in literature up to date. These horses perform special walking gaits with high poll flexion of the neck. Our goal is to evaluate the upper airway mechanics in CPH, showing abnormal respiratory sounds and poor performance during exercise. Resting and overground endoscopy was performed in 40 CPHs. Statistical analyses were performed using the sciPy package. One-tailed Fisher exact tests were used to check for positive contingency between each pair of upper respiratory tract disorder (P < .05). Arytenoid cartilage collapse was observed in 35 of 40 cases during exercise. Among these, dynamic laryngeal collapse (DLC) was the most significant finding, but ventromedial luxation of the apex of the corniculate process of the arytenoid and recurrent laryngeal neuropathy was also observed. Dorsal displacement of the soft palate was only detected in 4 of 40 cases. DLC was significantly associated with vocal cord collapse, nasopharyngeal collapse, and medial collapse of the margins of the epiglottis, and medial collapse of the margins of the epiglottis was associated with nasopharyngeal collapse. DLC is only a typical feature in some special breeds worldwide. We suggest that the extensive poll flexion and the relatively small laryngeal lumen and high intensitivity workload are the most important predisposing factors of DLC. Ventromedial luxation of the apex of the corniculate process of the arytenoid was over-represented in our caseload, compared with other studies. Whereas, despite the intensive workload, dorsal displacement of the soft palate was relatively uncommon. We presume that this could also be tailored to the high poll flexion performed during the special gaits.

Asthmatic Disease as an Underlying Cause of Dorsal Displacement of the Soft Palate in Horses.

It is important to treat the upper and lower respiratory tracts as a single unit, as lower respiratory tract diseases can often cause upper respiratory functional disorders, whereas upper respiratory obstructions could be a factor in lower respiratory problems. The present study aimed to investigate the hypothesis that asthmatic diseases may be an underlying cause of dorsal displacement of the soft palate in horses. Pleasure or sport horses (n = 57) with a history of asthmatic disease were incorporated in the study. All horses were examined in the exacerbation phase of the asthmatic disease. Bronchoalveolar cytology and tracheal lavage bacteriology were performed in all cases. The upper respiratory tract was evaluated at rest in all horses and during exercising endoscopy in 11/57 with severe equine asthma. Binomial tests with P ≤ .05 significance were used to establish estimated intervals of the measured frequencies of dorsal displacement of the soft palate (DDSP) occurring in the studied groups. It was observed that more than 60% of horses with mild or moderate equine asthma and more than 79% of horses with severe equine asthma are presented with DDSP during resting endoscopy examination. During the exercising endoscopy, DDSP was detected in all cases of severe equine asthma. These findings support the proposed hypothesis that DDSP was common in horses with equine asthma. Both increasing negative pressure in the airways due to bronchoconstriction and inflammatory processes could be factors in the development of DDSP. The consequent step would be to investigate the same population of horses in the remission phase of the equine asthma.

Serum neutralising antibody titres against a lineage 2 neuroinvasive West Nile Virus strain in response to vaccination with an inactivated lineage 1 vaccine in a European endemic area.

In the last decade in Hungary and the neighbouring countries, West Nile Neuroinvasive Disease (WNND) has been caused in dramatically increasing numbers by lineage 2 West Nile Virus (WNV) strains both in horses and in humans. The disease in this geographical region is seasonal, so vaccination of horses should be carefully scheduled to maintain the highest antibody titres during outbreak periods. The objective of this study was to characterise the serum neutralising (SN) antibody titres against a lineage 2 WNV strain in response to vaccination with an inactivated lineage 1 vaccine (Equip® WNV). Thirty-two seronegative horses were enrolled in the study, 22 horses were allocated to the vaccinated group and 10 retained as unvaccinated controls. Horses were vaccinated according to the product's vaccination guidelines. A primary vaccination of two doses administered 28 days apart was initiated approximately 5 months before the WNV outbreak season, followed by a booster vaccination one year later. Blood samples were collected during a 2-year period to monitor production of SN antibodies against lineage 1 and the enzootic lineage 2 WNV strain. Mean antibody titres against lineage 1 WNV were significantly higher (P ≤ 0.05) in the vaccinated group compared to the control group at all-time points after the primary dose of vaccination. Similarly, mean antibody titres against lineage 2 WNV were significantly higher (P ≤ 0.05) in the vaccinated group compared to the control group at all time-points except at 6 months after the primary vaccination. SN antibody titres were significantly higher against lineage 1 than lineage 2 at all-time points. According to the results, vaccination with an inactivated lineage 1 vaccine induces antibodies against both WNV lineages 1 and 2 strains up to 2 years after booster vaccination, but in those geographical regions where lineage 2 strains are responsible for seasonal outbreaks, a booster vaccination should be considered earlier than 12 months after primary vaccination.

Correction: Anticipatory response before competition in Standardbred racehorses.

[This corrects the article DOI: 10.1371/journal.pone.0201691.].

Anticipatory response before competition in Standardbred racehorses.

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.

Comparison of assays for the detection of West Nile virus antibodies in equine serum after natural infection or vaccination.

West Nile virus (WNV) mainly infects birds, horses and humans. Outcomes of the infection range from mild 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 haemagglutination inhibition test (HIT), enzyme-linked immunosorbent assay (ELISA) and plaque reduction neutralisation test (PRNT). Altogether 224 animals were tested by HIT for WNV antibodies and 41 horses were simultaneously examined by 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's 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 (26%) naturally exposed horses. Sera from 57/66 (86%) vaccinated animals were positive before the first booster and from 11/11 (100%) before the second booster. HIT was less sensitive for detecting IgG antibodies. We could detect postvaccination IgM in 13 cases with IgM antibody capture ELISA (MAC-ELISA) and in 7 cases with HIT. WNV is endemic in Hungary and regularly causes natural infections. Protective antibodies could not be measured in some of the cases 12 months after primary vaccinations; protection is more reliable after the first yearly booster. Based on our findings it was not possible to differentiate infected from recently vaccinated horses using MAC-ELISA. HIT cannot be used as a substitute for ELISA or PRNT when detecting IgG, but it proved to be a useful tool in this study to gain statistical information about the tendencies within a fixed population of horses.