Worming your horse

You can download faecal worm egg count submission forms here:

Individual sample

Multiple samples (yards)

How to take a sample for a faecal worm egg count

How to package a faecal sample for posting

How to use the EquiSal Tapeworm Test Kit


Worms are internal parasites that can do irreversible damage to the gut and other organs and be responsible for poor body condition, respiratory issues, colic and even fatalities.

Developing a targeted and appropriate worming programme for your horse is incredibly important for their welfare. There is a growing problem with worm resistance to our existing worming products. We need to fight this problem and preserve what products we have, as there are no more in development. In order to achieve this there are a few steps you can follow to keep on top of worm burdens and reduce the build-up of resistance.

We advise to only treat horses that need it; this can be managed by worm egg counts (WEC). The result of your WEC will determine if the horse requires treatment. WEC do not detect tapeworm, bots and encysted small red worm- therefore these have to be targeted at certain times of the year.

We do not aim to eradicate all worms from your horse. Horses can carry a small worm burden and be healthy. It is also important to maintain a small population to help reduce resistance.

Every horse is an individual, even horses sharing the same paddock should be treated individually. Some horses are more susceptible to higher worm burdens than others. Giving too small a dose could increase the risk of resistance and there is no additional benefit from giving too large a dose. Therefore it is important to dose accurately.

The Horse Health Programme includes 4 faecal worm egg counts, an autumn tapeworm saliva test and an appropriate autumn wormer as some of its many benefits.

Top Tips for Worm Control

Effective worm control relies on the correct and responsible use of wormers combined with good pasture management.

  • Use Faecal Worm Egg Counts (FWEC) during the year to assess which horses need worming. Generally treat horses with a worm egg count greater than 200 eggs/g.
  • Target the following worms at the correct time of year with a wormer effective at killing them:
    • Encysted Redworm Larvae - late autumn/winter;
    • Bots - winter;
    • Tapeworm - autumn.
  • Worm all horses and ponies at the same time with the same product.
  • Use the correct dose: the recommended dosage will vary according to the horse’s weight. Estimate weight as accurately as possible using scales or a weigh tape.
  • Don’t rely on the blanket use of the same wormer: this may encourage the development of drug resistance in the parasite population.
  • Rotate the active ingredient for each grazing season: select one product type and use for the entire grazing season.

A well-managed pasture will help to reduce the worm burden.  The following points should be followed where possible:

  • Remove droppings on a regular basis (preferably daily, but at least twice a week) and don’t use horse manure as fertiliser.
  • Don’t overstock pastures: a maximum of two horses per hectare or 1-1.5 acres per horse is recommended.
  • Graze horses of a similar age together – young horses are more susceptible to a higher worm burden.
  • Sub-divide grazing areas into smaller paddocks and graze on a rotational basis.
  • Harrow pasture during dry conditions to expose soil-borne larvae so that they dry out and die.
  • Graze paddocks with other livestock too. This will dilute the horse worm burden on your pasture.

Worming in the Autumn/Winter

Whilst most of us understand the need to ensure that our horses do not develop significant worm burdens, there is evidence to suggest that many of us are not treating our horses in the most effective way. With an increasing risk of resistance to wormers, it is vital that we adopt a proper targeted worming programme to protect horses and ponies from the threat of irreversible damage. 

Why is a targeted worming programme important? 

  • Because of the increasing resistance to the active ingredients used in wormers
  • So that we do not worm our horses when it is unnecessary to do so, which is better for our horses and helps prevent the development of resistance
  • So that we can target the right worms at the right time of the year

In the autumn/winter, we should treat our horses for: 

  • Tapeworm (if indicated necessary following a tapeworm saliva test) - Autumn
  • Encysted small redworm larvae – Late autumn/winter after the first frost
  • Large redworm and bots - Autumn/winter

Which type of wormer is appropriate will depend on the results of a tapeworm test. 

What are tapeworms?

Tapeworms are the biggest worms to affect horses in this country. While the most common type can grow up to 20cm long, there is a much rarer type that can grow to a whopping 80cm in length!

Tapeworms are white, flattened, segmented worms that rely on the harvest mite to help them complete their lifecycle to infect horses; the mite ingests tapeworm eggs from dung and the horse inadvertently ingests harvest mites when eating forage. The larvae then develop into adult tapeworms in the horse’s digestive system. They can result in a number of health-related problems, ranging from loss of condition to colic.

Tapeworms won’t reliably show up in a standard faecal worm egg count.  This is because the tapeworm eggs are contained within the body segments of the tapeworm, which intermittently break off to be passed out in droppings.  It is sometimes possible to pick up some tapeworm eggs on a faecal egg count but because of the intermittent shedding and containment in body segments, absence of eggs seen does not rule out tapeworm infection. Therefore, even if your horse has a negative faecal worm egg count it could still have a tapeworm burden.

We can test for tapeworm using a saliva test or a blood test.

What is a Tapeworm Saliva Test?

  • It is a test which measures the antibodies to the tapeworm parasites that are present in the horse’s saliva. Unlike the other method of testing which involves a blood test, owners can take the samples for the test themselves without the need for a vet.
  • Saliva is taken from the horse’s mouth using a simple swab collection kit. Horses should not have eaten, drunk or been exercised for 30 minutes before sampling to stabilise salvia concentration levels.
  • The swab is returned to the manufacturers for testing using a pre-paid envelope. The results will give a score and determine whether worming for tapeworm is required.
  • Results are reported to the lab at B&W if the test was purchased from us or provided under the Horse Health Programme.

A tapeworm test kit is available to buy from B&W Equine Vets or, if your horse is registered on the Horse Health Programme, a test kit is supplied to you in the autumn as one of the benefits.

How to use the saliva tapeworm test kit.

The test can remain positive for up to 4 months after tapeworm treatment. Talk to your vet as to whether your horse needs to be treated if this is the case.

What are encysted small redworm and what are the dangers?

Small redworm larvae can encyst within the horse’s gut wall throughout the year – especially in autumn and winter. Typically, sudden mass emergence of larvae will occur in spring, damaging the gut, which can cause diarrhoea and colic. This condition is known as larval cyathostominosis and has a mortality rate of up to 50%.

Hidden within the gut wall, encysted small redworm larvae can account for up to 90% of the redworm burden in a horse.

Control needs to be focused on all stages of the parasite’s lifecycle, with specific attention paid to the encysted larvae.

You can watch a video about why encysted small redworm larvae are a serious health threat to your horse here: Dangers of encysted small redworm larvae 

Why is it not necessary to carry out a faecal worm egg count at this time of year? 

For most times of the year, whether we need to worm our horses and with what type of wormer, should be based on the results of a faecal worm egg count (FWEC), ideally carried out every 12 weeks.  

However, in the autumn/winter season, it is recommended that you treat your horse for encysted small redworm which cannot be detected by a FWEC. Treatment should be after the first frost using a wormer containing moxidectin, which also treats redworm and bots, which is why it is not necessary to carry out a FWEC at this time of year.   

If the results of a tapeworm test suggest that you need to treat your horse for tapeworm as well as encysted small redworm larvae, a wormer containing both praziquantel (to treat tapeworm) and moxidectin will be needed. 

Why do we wait until after the first frost to worm our horses in the autumn/winter?

  • This is so that re-infection from larvae on the pasture is minimised.

How can I ensure that I give the correct dose?

When worming your horse, it is very important that you give the correct dose. Not giving enough will not only reduce the effectiveness of the wormer but also aid resistance to it. Most wormers are very safe but accurate dosing is probably more important for young animals as their weight is often more difficult to estimate. Ask for help from your vet if this is the case. If you do not have access to a weigh bridge, a weigh tape can provide a useful estimate of weight.


We offer faecal worm egg counts, tapeworm saliva tests and have a range of wormers available at very competitive prices. Contact your local B&W Clinic for prices and further details.

Why getting worming right is easy with the Horse Health Programme

Get the best preventative health care for your horse and spread the cost in equal monthly payments.

The Horse Health Programme includes an autumn tapeworm test, an autumn wormer and four faecal worm egg counts as some of its many benefits, making effective and targeted worming as easy as possible for you.

Contact your local B&W Clinic to register.

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