Increased freedom of head movement mitigates stress and bacterial load in the airways of horses during transport

Yuji Takahashi; Hidekazu Niwa; Yusaku Ebisuda; Kazutaka Mukai; Toshinobu Yoshida; Sharanne Raidal; Barbara Padalino; Hajime Ohmura

doi:10.3389/fvets.2024.1477653

Increased freedom of head movement mitigates stress and bacterial load in the airways of horses during transport

Front Vet Sci. 2024 Oct 4:11:1477653. doi: 10.3389/fvets.2024.1477653. eCollection 2024.

Authors

Yuji Takahashi¹, Hidekazu Niwa², Yusaku Ebisuda¹, Kazutaka Mukai¹, Toshinobu Yoshida¹, Sharanne Raidal³, Barbara Padalino^{4

5}, Hajime Ohmura⁶

Affiliations

¹ Sports Science Division, Equine Research Institute, Japan Racing Association, Tochigi, Japan.
² Microbiology Division, Equine Research Institute, Japan Racing Association, Tochigi, Japan.
³ School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia.
⁴ Department of Agricultural and Food Sciences, University of Bologna, Bologna, Italy.
⁵ Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia.
⁶ Miho Training Center, Japan Racing Association, Ibaraki, Japan.

Abstract

Introduction: Protection of horse welfare during transport is crucial. The aim of this study was to determine the effect of head and neck restraint on behavior and airway bacteria.

Methods: In a randomized crossover study, six healthy Thoroughbreds were transported by road for 22 h in an individual bay with tight head restraint (50 cm short-rope) or loose head restraint (95 cm long-rope). Behavioral parameters relating to head position, eating, and stress were monitored during transportation. Tracheal wash samples were obtained 6 days before and immediately after transport for bacterial culture and metagenomic analysis.

Results and discussion: Compared to before transport, bacterial load (CFU/mL) after transport was significantly increased in the short-rope group (p = 0.04), whereas no changes were observed in the long-rope group. Transport significantly reduced Simpson index at phylum, class, order, and family levels in both groups (p < 0.001) of tracheal microbiota. In both groups, this reduction was associated with increases in the dominant members of relative abundance at phylum (Firmicutes: +24% in long-rope and +14% in short-rope), class (Bacilli: +20% in long-rope and +22% in short-rope) and family (Streptococcaceae: +22% in long-rope and +23% in short-rope) levels. Licking behavior during transportation with short-rope restraint was more frequent than in horses with long-rope restraint. These results suggest loose head restraint during transportation is likely to ameliorate stress and mitigate the associated increased bacterial load in the lower airways associated with transport. Further, head position during transportation is likely a more important determinant of airway hygiene and distress than duration of travel.

Keywords: colony forming unit; equine; long-distance transport; microbiota; tracheal wash; welfare.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. The authors declare that this study received funding from Japan Racing Association. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication.