Worming: Worming in autumn/winter

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As part of our Horse Health Programme (HHP), we are keen to help you protect your horse against worms. The best way to keep horses safe, now and in the future, is to practice targeted worming using diagnostic tests and risk assessments to determine if you need to worm your horse. We can use faecal worm egg counts to do this during the grazing season, but in the autumn/winter, we need to use different diagnostic tests to identify whether your horse needs to be treated for tapeworm and/or encysted small redworm as neither of these can be identified using a faecal worm egg count.

A simple saliva test, provided as one of the HHP benefits can be carried out to determine whether your horse needs to be treated for tapeworm.

When it comes to – small redworm larvae, including encysted larvae, advice on treating them is changing. In the past, you may have been recommended to routinely treat all horses with moxidectin at the end of the grazing season when the weather turns colder. However, specialists and experts in veterinary medicine who have been brought together to look at the issue of resistance and to develop best practice, are now recommending that we perform a risk assessment, and in some cases a blood test, before treating a horse for small redworm larvae. This is for several important reasons:

  • To reduce resistance. Similar to antibiotics, resistance to the ingredients used in wormers is a real and rapidly growing concern. It is fuelled by routine and over-use of wormers. This is a global problem and there are no new alternative ingredients on the horizon. Only treating horses when necessary will help to slow down the growing rate of resistance.
  • To avoid treating a horse unnecessarily, which is better for the horse. Many horses are at a low risk of small redworm larvae infection.
  • Concern about the serious environmental toxic effects of equine parasiticides on invertebrates, aquatic animals and other organisms. These drugs are excreted in treated horses’ droppings, which rapidly contaminate pastures and groundwater.

If we are to preserve the effectiveness of wormers for the future, we must all take responsibility and move towards a risk-assessed and diagnostic-led worming programme for our horses, rather than worming routinely. If you would like further information about a suitable worming programme for your horse or more information about the small redworm blood test and risk assessment, please speak to your vet.

What are the dangers of tapeworms and small redworm larvae?

  • Tapeworms can cause digestive disturbances, loss of condition and colic if a horse develops a large burden of worms.
  • Small redworm larvae can encyst within your horse’s gut wall throughout the year -especially in the autumn and winter. If the larvae are present but not treated, a sudden mass emergence of larvae may occur in the spring, damaging the gut, which can cause diarrhoea and colic.

Your vet will recommend a suitable wormer if one is required, and also provide advice on the best time to administer it to minimise the risk of pasture recontamination.

Four faecal worm egg counts, an autumn/winter tapeworm saliva test and an appropriate autumn/winter wormer (if one is required) are included in the benefits when you join the Horse Health Programme.

Important points

For safe and effective worming, follow these tips:

  • Use a diagnostic-led, targeted worming programme all year round and always use the correct wormer if you need to worm your horse.
    • Contact your veterinary practice for advice on a suitable worming programme.
    • Do not use any wormers unless you need to; overuse will encourage resistance and is not good for your horse.
  • Know your horse’s weight; give the correct amount of wormer
    • Under-­dosing encourages development of resistance

If you need more information, just contact your local Horse Health Programme practice for expert advice. We can provide best practice, up-to­‐date recommendations on any aspect of parasite control.