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Service Information

  • Worming

    Worming is a vital part of your horse’s preventative health care regime. We provide a comprehensive approach to effective worm control, focusing on monitoring and targeted strategic use of wormers, in an aim to reduce anthelmintic resistance.

    To make monitoring and managing your horse’s worm burden as easy and simple as possible we have established a yearly worming programme; this aims to provide you with a complete worming package for your horse all year round.

    The strategic worming programme includes:

    1. Three faecal  worm egg counts which are performed at three monthly intervals in the spring and summer

    2. One Equest  Pramox Wormer, used in late Autumn, after the first frost, to target encysted red worm and tapeworm

    3. Worming Year Planner

    4. Veterinary advice on when worming is required and guidance in developing the best worming strategy to suit your individual horse’s needs.

    For young, elderly or pregnant horses, additional worming and monitoring is sometimes required.

    An effective, strategic worming programme considers all the factors involved to enable us to manage your horse’s individual worm burden. This is not only much better for the long term health of your horse, but also reduces reliance on worming, therefore minimising the development of resistance and the cost of buying wormers regularly.

    How can we reduce resistance?

    Resistance to wormers occurs when a parasite population is not longer susceptible to a drug. This can develop due to inaccurate dosing, overuse of one type of wormer or worming too frequently.

    Accurate dosing: Ensure you are giving your horse the correct dose by estimating their weight using a weight tape. Even better – ask us to put them on the weigh bridge if you are at the clinic!

    Worming only when necessary: By performing faecal worm egg counts (FWEC), we can detect the number of roundworm eggs in the faeces; a worm egg count of greater than 300 eggs/gram indicates worming is required. As FWECs do not detect encysted redworm, tapeworm, pinworm or bots, all horses should be wormed once yearly in Autumn.

    To perform a worm egg count we need 1/2 of one faecal ball (as fresh as possible) in a sealed container or bag.

    Pasture Management

    Good management is essential in reducing the worm burden on the pasture and therefore the number of worm eggs your horse will ingest whilst grazing.

    1. Regularly ‘Poo Picking‘ fields  (at least twice weekly during summer and once a week in winter) reduces the number of worm eggs that develop into larvae and contaminate the pasture.

    2. Avoid Overstocking by having no more than 2 horses per acre

    3. Grazing with cattle or sheep. Worms are host specific so this can be an effective way of reducing worm eggs on the pasture.

    4. Resting the pasture for 3 months of the year allows time for worm eggs to be killed by either direct sunlight in the summer (aided by harrowing) or harsh frosts in  the winter.


    Horses are affected by several types of worms, which can cause issues varying from no clinical signs at all to weight loss, diarrhoea and colic. The good news is that by following a strategic worming programme, these issues can be prevented. However, as resistance to the drugs we use is developing further, it is becoming even more important to ensure we are not overusing wormers and they are still effective at treating the parasites we are targeting.


    Small Redworms are the most common internal parasite. Throughout the summer the eggs are shed in faeces and your horse’s worm burden can be assessed using faecal worm egg counts (FWECs). In winter months, the worms hibernate in the gut wall (encysting) and then emerge on-mass in early spring, which causes huge damage to the gut lining and leads to diarrhoea, weight loss and sometimes even death. Every horse should be wormed once a year in late autumn/winter with moxidectin (Equest) to treat any encysted redworm.

    Large redworms are now uncommon due to improved worming regimes and effective treatments. The larvae can migrate through blood vessels, causing clots which disrupt the guts’ blood supply and can cause serious colic, often requiring surgery. The eggs are seen on FWECs.

    Ascarids are large roundworms that are most commonly seen in younger horses, leading to poor growth, digestive and respiratory problems. The worms can grow up to 50cm in length and cause obstructions in the small intestine. The larvae migrate through the lungs, so horses may also develop a cough.

    Small redworms
    Close up of a redworm
    Ascarid impaction in the small intestine
    Tapeworm in the intestine


    Tapeworm can infect horses all year round, with exposure being greatest during prolonged periods of grazing. High tapeworm burdens can cause diarrhoea and bouts of colic. Faecal worm egg counts cannot monitor tapeworm burdens; we recommend that horses either be blood tested or wormed for tapeworm once a year at the end of the grazing season with a wormer containing praziquantel (e.g. Equitape, Equest Pramox).


    These worms live in the horses rectum and lay their eggs around the anus, which can cause significant irritation and itching of the tail head. Wormers used for treating other worms used to be effective, but recently increased resistance has been seen. Fenbendazole wormers (e.g. Panacur) are currently thought to be most effective, alongside meticulous stable hygiene, however treatment can be frustrating.



    Bot flies lay their eggs on the horse’s coat, which are then accidentally ingested as the horse grooms itself. The eggs then mature to larvae in the horse’s stomach. Bot egg removal during the summer and worming during the winter months should successfully treat the parasites.