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Horse Worming to avoid Tapeworm, Encysted Redworm and Bots.

 worming horses

Increased Resistance Means it’s Vital to Plan Ahead When Worming Horses.

Shorter Days and Longer Nights mean it’s Time to Think About Worming Horses.


Worming horses seems to be a constant cause of confusion amongst horse owners and this is not surprising given the many different views and opinions on the subject. With the increasing threat of resistance in our UK horse worm population it is vital that horse owners follow a sensible worm control programme and enlist the help of their vet or SQP.


With the days getting shorter and the nights drawing in we now need to think about worm control in our horses and ponies over the winter months. So which worms do we need to worry about?



Tapeworm has become a more important parasite of horses especially since the association between tapeworm infection and colic in horses was described. Tapeworm causes areas of damage to the lining of the gut where the tapeworms attach and feed. This can affect the normal motility of the gut leading to spasmodic colic and, in very heavy infestations, can cause impaction colic. 



Small redworm or cyathostomes as they are also known are of particular importance at this time of the year because of the parasites ability to ‘encyst’ within the gut wall. The larvae picked up from pasture burrow into the lining of the gut and hide away there in a dormant state. Damage caused to the gut wall during the encysting phase can cause diarrhoea and mass emergence of the encysted larvae, which usually occurs in the spring, can lead to severe diarrhoea and colic.



Bots are the larval stage of the bot fly and although rarely cause disease, can be associated with gastritis (inflammation of the stomach) and recurrent colic in horses and ponies. Horses pick up bots from mutual grooming and ingesting the eggs that are stuck to hairs of the horse’s coat.


It is estimated that 80% of the worms will be found in 20% of horses, suggesting that horses sharing the same paddock may have very different worm burdens. This highlights the need for each horse’s worming requirements to be considered on an entirely individual basis. 


Following a strategic worming plan will help you to meet the individual worming needs of your horse. Worm planners can act as a great starting block, with advice on the use of faecal worm egg counts, pasture management and rotation of drug groups which will, in turn help to reduce the development of resistance.


Resistance occurs when a worm is able to survive a standard dose of wormer. When this happens the drug will no longer be effective at treating those worms that have become resistant. Resistance is irreversible, so once the worm population on your yard has developed resistance, they will always be resistant and will produce resistant offspring.


With the ongoing issues this brings, we need to be using faecal worm egg counts to tailor worm treatments to only those horses that actually require it. Faecal worm egg counts will detect roundworm infection picked up during the grazing season. It is important, however, to remember that tapeworm, encysted redworm and bots cannot be detected using a faecal worm egg count. 


There are blood tests available to identify exposure to tapeworm but no test is yet available for the detection of encysted redworm. Therefore in the autumn (October/November) it is important to treat for tapeworm and bots and a treatment for encysted redworm must be given well before the spring. Only certain products are suitable for treating tapeworm, bots and encysted redworm, so it is worth discussing worm control with your vet/SQP to ensure you are using the appropriate drug group at this time of year. Dose your horse as accurately as possible for their weight, weight tapes can be very helpful as a general guide.


See our range of horse wormers


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 Newsletter 606

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