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Worming your horse - responsible parasite control

Parasitic intestinal worms are common, and all grazing horses are likely to have worms. However, most horses have a very low number, which causes no negative side effects or harm to the horse.

Problems only arise when the worm burden increases. A large burden of worms can cause clinical symptoms such as weight loss, diarrhoea, colic, and in extreme cases, worms can be life-threatening.

Our Equine SmartPlan is a monitoring-based approach to reducing wormer resistance by avoiding unnecessary treatment, which also saves you money.

Learn about our SmartPlan


Why Penn Equine Vets approaches worming differently

There is growing concern about worming resistance in the horse population largely caused by the overuse of wormers. In the UK, resistance to all currently available wormers has been identified.

Resistance is when the drug used in a wormer to treat a worm burden, fails to kill the worms. This could potentially lead to life-threatening burdens of worms in horses that are impossible to treat. Unfortunately, there are no new medications to treat worms, so the key is protecting the ones we do have.

Using worm egg counting to identify those horses’ requiring treatment, leads to a reduction in the number of wormer doses needed, and preserves the effectiveness of wormers for the future equine population.

Worming resistance is caused by:

  1. Overuse of wormers
    Worming your horse kills the worms in the gut that are susceptible to the worming drug, leaving behind only the worms resistant to that drug, which then multiply. If this is repeated at regular intervals, over time the resistant worms left behind after each worming treatment will multiply unchecked. This results in a large worm burden causing clinical disease that is resistant to worming medication and therefore impossible to treat.
  2. Incorrect dosing
    Administering a worming dose that is too low is another way to only kill a small proportion of susceptible worms, leaving the more resistant worms behind to multiply.
  3. Repeatedly using the same wormer
    Using the same wormer each time to treat your horse, repeatedly exposes the worms to the same drug. This will leave behind the worms that are resistant to that drug, which can then multiply unchecked to form a large worm burden.

How can we worm horses responsibly?

By following 3 simple rules:

  1. Monitoring – Testing your horse’s droppings for worms 3 times per year between April and October with a faecal worm egg count, and their saliva once a year for tapeworm.
  2. Targeted treatment – Treat only the horses that have a high worm egg count (>200 epg).
  3. Management – Worms are passed on to horses in their droppings. Good stable and pasture hygiene by removing droppings regularly reduces the source of worm infection. We recommend mucking out your horse’s stable at least once a day and removing droppings from the pasture at least twice a week. Co-grazing your horses with cattle or sheep can also be helpful, as well as not overstocking your pasture. Tapeworm is passed though harvest mites in forage.

For more advice about equine worming and healthcare, contact Penn Equine Vets . Join Penn Equine Vets’ Smart Plan & tackle worming head-on.

Learn about our SmartPlan


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