Control and anthelmintic resistance of horse helminths in Vilnius district

Equine helminths are one of the major health problems in horses. For many years it has been addressed by the irrational use of anthelmintics resulting in a worldwide increase of helminth anthelmintic resistance. The purpose of this study was to determine the level of horse helminth infection, the effectiveness of applied treatment and to evaluate the efficacy of two anthelmintics – ivermectin and pyrantel – in five stables of Vilnius district, Lithuania. In the beginning of the study fresh fecal samples were collected before (day 0) and 14 days after treatment. The likely effects of equine age, sex, horse antiparasitic treatment scheme and prophylactic measures on equine helminth infection before treatment (day 0) were taken into consideration. Only horses with an EPG≥100 were included into the study. Afterwards, horses were divided into three groups: Group A was treated with ivermectin; Group B – with pyrantel, and Group C was not treated (Control). Given the results of the study, the efficacy of ivermectin and pyrantel for the treatment of strongyles and ascarids was compared by calculating FECRT. Cases of anthelmintic resistance were recorded. All tested horses (n = 82) were infected with strongyles. Ascarid infection was only detected in a part (n = 20) of horses. It was found that young horses (1-4 years) had the highest prevalence of strongyles. Adult horses (5-15 years) had 19,23 % lower and senior horses (16-26 years) had 60,55 % lower prevalence than young horses (p <0,05). Infection with ascarids was 18,89 % lower in young horses and 29,17 % lower in adult horses than in senior horses (p <0,05). The males were 18,92 % less infected with strongyles and 5,79 % less infected with ascarids than females. In our data there was no statistically significant difference in EPG‘s to horse sex (p≥0,05). The results of the study showed that horses whose medication is rotated were 53,13 % less infected with strongyles and 62,12 % less with ascarids than those receiving the same anthelmintic drugs (p <0,05). Horses who received parasitological stool sample examination were shedding 21,68 % less strongyle eggs than those with no examination done. Ascarid infection for tested horses was also 48,12 % lower (p≥0,05). The efficacy of ivermectin was 99,9 % according to the fecal egg count reduction test (FECRT) and decreased efficacy of pyrantel of 89,8 % (p <0,001) was detected. There have been found five cases of strongyle AR for pyrantel. IVM and PYR were 100 % effective for the treatment of ascarids (p