A survey of UK horse owners on equine internal parasite management, testing, and treatment resulted in 4,232 usable responses. The survey was distributed through veterinary practices, equestrian organisations,and other means from December 2021 to October 2022. Key survey questions were about pasture management, parasite testing, and worm-associated illnesses. 

The researchers published the results of this study in two parts. The first was, “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.” The second was focused on anthelmintic use.

The authors of these papers were J. Shrubb, N. Robinson, D. Rendle, I. Schofield, C. Scott, J. Crabtree, G. Hunter, R. Dean, R. Parker, T. Mair

The reason for the survey was because the authors felt that, “Anthelmintic resistance in equine parasites is increasing. Pasture management is a vital component of helminth control; its implementation is key to reducing anthelmintic dosing frequency to reduce selection pressure for resistance.

Management Results

Part 1 of the study noted the following management uses by survey respondents.

  • Only 21.5% of respondents alternated or co-grazed their horse with ruminants (higher for horses grazing on private properties compared to horses grazing on livery yards).
  • The majority of owners (73.3%) removed faeces from pastures (poo-picking)
  • Of those, 86.4% removed faeces twice a week or more.
  • Owners of horses pastured individually were more likely to poo-pick (89.8%) than horses pastured in groups (68.9%).
  • Three-quarters of respondents (77.1%) rested pastures, but less than 5% for more than 6 months.
  • Only 5.1% of owners reported they had experienced illnesses related to worms in any horse (most common clinical signs were colic and weight loss).

The researchers said, “Optimising management practices should reduce the requirements for using anthelmintics to achieve parasite control, thereby reducing selection pressure on the development of resistance.”

Anthelmintic Results

Part 2 of the study resulted in the following responses:

  • Owners of horses on livery yards were less likely to make anthelmintic-use decisions than those on private properties.
  • Managers made decisions in 39.6% of horses on livery yards.
  • 52.0% administered anthelmintics based on faecal egg counts (FECs)/tapeworm ELISA results, but 30.0% gave anthelmintics at least annually regardless of any results.
  • Owners who sought veterinary advice were more likely to administer anthelmintics based on test results.
  • The frequency of routine deworming was higher if owners/managers did not test.
  • 88.9% dewormed all horses on pasture at the same time.
  • Moxidectin was the first choice for 82.2% of owners.
  • Regular FECs were performed by 84.7%; higher for those who sought veterinary advice (89.3%).
  • Tapeworm ELISAs were utilised by 40.8%; higher for those on a health programme (68.1%)
  • 58.5% of horses were routinely treated for tapeworms regardless of test results.

The summary for this part of the survey research noted, “The uptake of diagnostic testing, particularly FECs, was higher than previously reported, but routine anthelmintic use was still common. Horse owners who sought advice from their veterinarian, or whose horse was enrolled in a health programme, were more likely to take a diagnostic-led approach to parasite control.”

Final Words

This survey showed the use of internal parasite testing was higher than previously reported in the UK. However, scheduled use of anthelmintics without testing was still in vogue. Working with your veterinarian (no matter where you live) to reveal high parasite shedders and horses that need more or less frequent deworming is better for the horse, the environment, and will help protect anthelmintics from increased resistance.

Using management techniques such as manure removal from pastures also are good to help reduce the parasite burden in the environment.

Further Content

  • Kimberly S. Brown
    Kimberly S. Brown is an award-winning writer and publisher. She is the Editorial Director for My Senior Horse. Brown spent 10 years at Equine Network, parent company of My Senior Horse. Prior to that she worked for three years in equine nutrition after she retired from nearly 30 years working at The Blood-Horse. Brown spent the last 15 years of her time at that organization creating and developing The Horse and TheHorse.com.
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