Efficacy of combined therapy with fenbendazole and Bacillus amyloliquefaciens in treating strongylatosis in horses

The purpose of the research is to evaluate the efficacy of the combined use of fenbendazole and Bacillus amyloliquefaciens against Strongylata in horses, to compare the combined therapy to fenbendazole monotherapy, and to study the effect on the general clinical state of horses.

Materials and methods. The study was conducted on 20 horses divided into two groups of 10 animals. The horses from the experimental group were given fenbendazole once at a dose of 7.5 mg/kg, and the probiotic B. amyloliquefaciens daily at a dose of 50 mg/kg for 14 days. The control group of horses received only fenbendazole. The therapy efficacy was monitored by examining faeces using the flotation method on days 7, 10, 14, 16, 19, 22, 25, 28, 31, and 34 after treatment. On day 14 of the experiment, the test reduction rates in the number of eggs in faeces were calculated. To determine starting dates of repeated egg release, the values obtained on days 7 and 14 were used. Faecal microbiota was analyzed before the treatment and on day 14.

Results and discussion. Both groups of horses showed a reduction in Strongylata eggs in faeces after treatment with a gradual increase in their number by day 34 of the experiment. The first Strongylata eggs were detected on day 7 of the therapy. The period of repeated release of Strongylata eggs was two weeks in the experimental and control groups. Test reduction rates of eggs in faeces were below 90% on day 14 in both groups. The analyzed faecal microbiota did not reveal significant changes after the probiotic, although Aspergillus fungi disappeared in the experimental horses. Throughout the study, the horses in both groups remained clinically healthy with no signs of gastrointestinal disorders. The combined fenbendazole and B. amyloliquefaciens did not result in any statistically significant increase in the deworming efficacy as compared to fenbendazole alone (P > 0.05). However, the combined anthelmintic and probiotic showed a certain biological advantage expressed in a decrease in Strongylata eggs after the treatment in the experimental group. Despite the lack of significant changes in the intestinal microbiota, the absence of Aspergillus spp. after administered probiotic may indicate its potential antifungal effect.

1. Bergey R., Holt J., Krieg N., Sneath P. et al. Bergey's Manual of Determinative Bacteriology: in 2 volumes, edited by G. A. Zavarzin. M.: Mir, 1997. (In Russ.)

2. Varlamova A. I., Arkhipov I. A., Khalikov S. S. New directions in the creation of innovative antiparasitic drugs. “Theory and practice of parasitic disease control”: a collection of scientific articles from the proceedings of the International Scientific Conference. 2020; 21: 72–80. (In Russ.) https://doi.org/10.31016/978-5-9902341-5-4.2020.21.72-80

3. Kokolova M. L., Gavrilyeva L. Yu., Pribylykh E. I., Popova N. V. Prevention and treatment of parasitic diseases in herd horses at the beginning of the cold period in Yakutia. Veterinariya i kormleniye = Veterinary medicine and feeding. 2024; 2: 35–39. (In Russ.) https://doi.org/10.30917/attvk-1814-9588-2024-2-8

4. Kokolova M. L., Gavrilyeva L. Yu., Stepanova S. M. Development and implementation of technique of combination therapy against strongylatosis in herd horses in Yakutia. Sbornik nauchnykh trudov Stavropol'skogo nauchno-issledovatel'skogo instituta zhivotnovodstva i kormoproizvodstva = Collection of scientific papers of the Stavropol Research Institute of Animal Husbandry and Fodder Production. 2014; 7 (2): 377–380. (In Russ.)

5. Panova O. A., Arkhipov I. A., Baranova M. V., Khrustalev A. V. The problem of anthelminthic resistance in horse breeding. Rossiyskiy parazitologicheskiy zhurnal = Russian Journal of Parasitology. 2022; 16 (2): 230-242. (In Russ.) https://doi.org/10.31016/1998-8435-2022-16-2230-242

6. Sutton D., Fothergill A., Rinaldi M. The determination of pathogenic and conditionally pathogenic fungi. M.: Mir, 2001; 352. (In Russ.)

7. Salkova D., Panayotova-Pencheva M., Movsesyan S., Beyer S., Voronin M., Arkhipov I. A. Alternative methods to control parasitic diseases in animals. Rossiyskiy parazitologicheskiy zhurnal = Russian Journal of Parasitology. 2014; 1: 93–103. (In Russ.)

8. Abd-Elgawad M. M. M. Towards sound use of statistics in nematology. Bulletin of the National Research Centre. 2021; 45: 13. https://doi.org/10.1186/s42269-020-00474-x

9. Cai Enjia, Wu Rongzheng, Wu Yuhong, Gao Yu, Zhu Yiping, Li Jing. A systematic review and meta-analysis on the current status of anthelmintic resistance in equine nematodes: A global perspective. Molecular and Biochemical Parasitology. 2024; 257: 111600. https://doi.org/10.1016/j.molbiopara.2023.111600

10. Cernea M., Carvalho L. M. M., Cozma V., Cernea I., Raileanu S., Silberg R. et al. Atlas of diagnosis of equine strongylidosis. Edutura Academic Pres. 2008; 120.

11. Chen Guojin, Fang Qianan, Liao Zhenlin, Xu Chunwei, Liang Zhibo, Liu Tong et al. Detoxification of Aflatoxin B1 by a Potential Probiotic Bacillus amyloliquefaciens WF2020. Frontiers in Microbiology. 2022; 13: 891091. https://doi.org/10.3389/fmicb.2022.891091

12. Costa M. C., Weese J. S. The equine intestinal microbiome. Animal Health Research Reviews. 2012; 13 (1): 121–128. https://doi.org/10.1017/s1466252312000035

13. Cruz C. S., França W. W. M., de Arújo H. D. A., Ximenes E. C. P. A., de Souza V. M., Albuquerque M. C. P. A. et al. In vitro and in vivo evaluation of Bacillus clausii against Schistosoma mansoni. Acta Tropica. 2022; 235: 106669. https://doi.org/10.1016/j.actatropica.2022.106669

14. Crotch-Harvey L., Thomas L. A., Worgan H. J., Douglas J. L., Gilby D. E., McEwan N. R. The effect of administration of fenbendazole on the microbial hindgut population of the horse. Journal of Equine Science. 2018; 29 (2): 47–51. https://doi.org/10.1294/jes.29.47

15. Hu Yan, Miller M., Zhang Bo, Nguyen T. T., Nielsen M. K., Aroian R. V. In vivo and in vitro studies of Cry5B and nicotinic acetylcholine receptor agonist anthelmintics reveal a powerful and unique combination therapy against intestinal nematode parasites. PLoS Neglected Tropical Diseases. 2018; 12 (5). https://doi.org/10.1371/journal.pntd.0006506

16. Jiang Zipeng, Su Weifa, Li Wentao, Wen Chaoyue, Du Shuai, He Huan et al. Bacillus amyloliquefaciens 40 regulates piglet performance, antioxidant capacity, immune status, and gut microbiota. Animal Nutrition (Zhongguo xu mu shou yi xue hui). 2023; 12: 116–127. https://doi.org/10.1016/j.aninu.2022.09.006

17. Joó K., Trúzsi R. L., Kálmán C. Z., Ács V., Jakab S., Bába A. et al. Evaluation of risk factors affecting strongylid egg shedding on Hungarian horse farms. Veterinary Parasitology: Regional Studies and Reports. 2022; 27: 100663. https://doi.org/10.1016/j.vprsr.2021.100663

18. Lyons E. T., Dorton A. R., Tolliver S. C. Evaluation of activity of fenbendazole, oxibendazole, piperazine, and pyrantel pamoate alone and combinations against ascarids, strongyles, and strongyloides in horse foals in field tests on two farms in Central Kentucky in 2014 and 2015. Veterinary Parasitology: Regional Studies and Reports. 2016; 3–4: 23–26. https://doi.org/10.1016/j.vprsr.2016.05.007

19. Nielsen M. K. Anthelmintic resistance in equine nematodes: Current status and emerging trends. International Journal for Parasitology: Drugs and Drug Resistance. 2022; 20: 76-88. https://doi.org/10.1016/j.ijpddr.2022.10.005

20. Nielsen M. K., von Samson-Himmelstjerna G., Kuzmina T. A., van Doorn D. V., Meana A., Rehbein S., Elliott T., Reinemeyer C. World association for the advancement of veterinary parasitology (WAAVP): Third edition of guideline for evaluating the efficacy of equine anthelmintics. Veterinary Parasitology. 2022; (303): 109676. https://doi.org/10.1016/j.vetpar.2022.109676

21. Rooney J., Cantacessi C., Sotillo J., Cortés A. Gastrointestinal worms and bacteria: From association to intervention. Parasite Immunology. 2023; 45 (4). https://doi.org/10.1111/pim.12955

22. Ye Jingkang, Wu Haiyang, Feng Li, Huang Qianghua, Li Qingxin, Liao Weiming et al. Characterization of Bacillus amyloliquefaciens PM415 as a potential bio-preserving probiotic. Archives of Microbiology. 2024; 206 (5): 222. https://doi.org/10.1007/s00203-024-03953-1

23. Zanet S., Battisti E., Labate F., Oberto F., Ferroglio E. Reduced Efficacy of Fenbendazole and Pyrantel Pamoate Treatments against Intestinal Nematodes of Stud and Performance Horses. Veterinary Sciences. 2021; 8 (3). https://doi.org/10.3390/vetsci8030042