CVS Equine develops and implements worm risk assessment tool for horses
8th July 2025
CVS Equine has become the first UK practice to co-develop and adopt a worm risk assessment tool for veterinary colleagues to use to support strategic and effective endoparasite control in horses.
The project aims to reduce anthelmintics (‘wormers’) use in horses; these anthelmintic drugs used to prevent and control parasitic worms, including intestinal redworms and tapeworms.
The move aims to help both reduce the risk of anthelmintic drug resistance in horses and to reduce the environmental toxicity of the drug excreted by the horse after treatment. Anthelmintic resistance among horse worms is a growing global problem that has been caused by the over-use of these drugs.
The new ‘What’s Your Worm Risk’ risk calculator was co-created by CVS Equine and Professor Jacqui Matthews of Austin Davis Biologics. The assessment tool looks at horse level factors - such as age and previous worm egg counts, along with management factors - such as field size, stocking density, dung removal, co-grazing with other animals and diagnostic testing.
It calculates the likely level of risk based on widely accepted principles of equine worm infections and, depending on horse-specific input, it will classify the risk of worm infection in an individual horse as low, moderate or high.
If a horse is deemed ‘low risk’ then worming with anthelmintics (including the use of moxidectin in the autumn/winter) may be omitted, whereas previously it has been recommended that all adult horses are treated in the winter for small redworms using moxidectin. This then has the effect of reducing the overall use of moxidectin in the equine population.
Charlotte Sinclair, Clinical Director at CVS Equine said:
“Wormer resistance is becoming a significant issue due to overuse. Guidelines now recommend only using wormers in a targeted way.
Our ‘What’s Your Worm Risk’ tool is underpinned by current research and recommendations. It should ideally be used alongside monitoring via faecal worm egg counts and other tests.
The tool will support prescribers across our practices when considering wormer use and how to apply best practice parasite control. It will also help to contribute towards future equine health and reduce equine veterinary medicine’s impact on the environment.”
The risk assessment tool has to date been used by CVS Equine practices in over 2,000 horses. To access the Worm Risk Assessment Tool visit the 'What's Your Worm Risk?' website.
CVS Equine provides a complete range of industry-leading veterinary services at 21 sites across the UK as well as its out of hours clinical and call answering services, Equicall and Equicomms. Its ambulatory veterinary surgeons are supported by a team of over 20 recognised Veterinary Specialists in internal medicine, surgery, dentistry, sports medicine, reproduction and diagnostic imaging based within a network of referral centres. The division offers a multi-disciplinary approach, along with the latest veterinary treatments, diagnostic services, advice, standards and support – as a result of unrivalled investment in people, equipment, facilities and research. For further information, visit the CVS Equine website.