Project WORMS (Working to Overcome Resistance and Make for a Sustainable Future): horse owner survey on equine parasite control in the UK. Part 1. Management factors

Background: Anthelmintic resistance in equine parasites is increasing. Pasture management is a vital component of parasite control, and is important to limit the development of resistance. Objectives : Investigate how horse owners use management procedures to control common intestinal parasites in horses. Study design : Online survey. Methods : Questionnaire distributed via practices, equestrian organisations, etc., December 2021 - October 2022. Combination of multiple choice, Likert scale and free text questions. Descriptive and inferential statistics performed in Microsoft Excel and IBM SPSS. Results : 4232 useable responses from the UK, predominantly England (85.4%). Premises included livery yards (45.7%) and private properties (51.1%). Most horses (70.4%) were aged 6-20 years. Over half (55.9%) were used for general riding/pleasure; 58.9% grazed with 1-3 other horses, while 20.7% grazed alone; 21.5% alternated or co-grazed with ruminants (significantly higher for horses grazing on private properties compared to horses grazing on livery yards; 73.3% of owners removed faeces from pastures (poo-picking), of which 86.4% removed faeces twice a week or more. Owners of horses pastured individually were significantly more likely to poo-pick (89.8%) than horses pastured in groups (68.9%); 77.1% of respondents rested pastures, but less than 5% for over 6 months. Only 5.1% of owners reported they had experienced illnesses related to worms in any horse (commonest clinical signs were colic and weight loss). Limitations : Selection bias. Conclusions : Results suggest a lack of understanding of the principles of non-chemical parasite control among many horse owners. Many owners (>25%) are not routinely poo-picking. Horses pastured alone or kept on a private property were significantly more likely to have their faeces regularly removed than thoses pastured in groups or kept on livery yards.