Abstract: Competitions are an important source of entertainment and revenue in the horse industry but may contribute to disease introduction and spread. The objectives of this study were to, (i) describe the annual (2016 to 2018) contact networks of Equestrian Canada competitions in Ontario, Canada, and (ii) determine if the networks exhibit characteristics of 'small world' networks. Data on Equestrian Canada registered competitions in the province of Ontario, Canada between 2016 and 2018 were used to create three types of yearly contact networks: competition networks, horse networks, and venue networks. Results: Dressage, hunter/jumper, and eventing competitions were connected through horses co-attending the same competitions; however, endurance and reining shows were isolates in these networks. The median node degrees in the yearly horse networks were between 567 and 619 with wide variation in node centrality scores. Horses competing in multiple disciplines at multiple levels had high node betweenness scores. Horse networks and venue networks had similarly short geodesics as random Erdös-Renyi networks of the same size but exhibited higher levels of clustering indicating that both the horse and venue networks meet the criteria for 'small world' networks. Conclusions: The high connectivity of the networks may provide opportunities for disease transmission to occur between competition levels and disciplines, and potentially increase case counts in an epidemic. The 'small world' topography of the competition and venue networks means disease spread could occur more rapidly in this population and the threshold for disease persistence may be lower.
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Overview
This study analyzed the contact networks formed through equine competitions in Ontario, Canada, from 2016 to 2018 to understand how these interactions might facilitate the spread of diseases among horses.
The research also examined whether these networks displayed ‘small world’ characteristics, which would suggest faster and wider disease transmission potential.
Objectives of the Study
To describe annual contact networks based on equestrian competitions registered with Equestrian Canada in Ontario between 2016 and 2018.
To determine if the networks exhibited ‘small world’ properties that could influence disease spread dynamics.
Types of Networks Created
Competition networks: Connections between different types of competitions based on shared horse participation.
Horse networks: Networks formed by horses attending multiple competitions or venues, indicating direct or indirect contacts between animals.
Venue networks: Networks connecting competition locations based on horses visiting the same venues across events.
Key Findings
Connectivity among disciplines:
Dressage, hunter/jumper, and eventing competitions were interconnected through horses that attended multiple events in these disciplines.
Endurance and reining competitions tended to be isolated within the networks, showing less overlap with other disciplines.
Node degree and centrality:
The median number of connections per horse (node degree) ranged from 567 to 619 annually, highlighting broad connectivity.
Horses participating in multiple disciplines and levels had higher betweenness centrality, meaning they acted as critical bridges within the network.
Network topology:
The horse and venue networks had short average path lengths (“geodesics”) similar to random Erdös-Renyi networks, which means any two nodes were only a few connections apart.
Both networks showed higher clustering than random networks, meaning nodes tended to form tightly knit groups.
This combination of short paths and high clustering fits the definition of ‘small world’ networks.
Implications for Disease Transmission
The high level of connectivity suggests diseases can spread across different competition disciplines and levels quickly.
‘Small world’ characteristics imply infectious agents can transmit rapidly and efficiently throughout the network, potentially leading to large outbreaks.
The threshold for disease persistence (i.e., the point at which an infection can sustain itself within the population) may be lowered due to these network properties.
Horses with high betweenness centrality could be targeted for increased surveillance or control measures because of their pivotal role in disease spread.
Conclusion
Equine competitions in Ontario form highly connected networks that facilitate substantial horse-to-horse contacts across multiple events and venues.
The ‘small world’ nature of these networks increases the risk and speed of infectious disease spread among competing horses.
Disease control strategies in equine populations should account for these network structures to effectively mitigate transmission during outbreaks.
Cite This Article
APA
Rossi TM, O'Sullivan TL, Greer AL.
(2025).
Descriptive network analysis of Ontario, Canada equine competitions: implications for disease control.
BMC Vet Res, 22(1), 43.
https://doi.org/10.1186/s12917-025-05248-z
Department of Population Medicine, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Animal Health Laboratory, University of Guelph, Guelph, ON, N1G 2W1, Canada.
O'Sullivan, Terri L
Department of Population Medicine, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Greer, Amy L
Department of Population Medicine, University of Guelph, Guelph, ON, N1G 2W1, Canada. amygreer@trentu.ca.
Department of Biology, Trent University, Peterborough, ON, K9L 0G2, Canada. amygreer@trentu.ca.
MeSH Terms
Animals
Horses
Ontario / epidemiology
Horse Diseases / prevention & control
Horse Diseases / epidemiology
Horse Diseases / transmission
Sports
Conflict of Interest Statement
Declarations. Ethics approval and consent to participate: All data are publicly available and therefore informed consent was not obtained from show participants. Our study design was reviewed and approved by the University of Guelph Research Ethics Board (REB#19-09-013). Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.
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