Preventative Medicine

Find out more about our worming package

Strategic Worming Package

A good de-worming strategy is an important part of your horse’s general healthcare plan. A high worm burden may predispose your horse to ill health, weight loss, poor condition, diarrhoea and most seriously, colic.

The traditional approach of treating horses for worms at set intervals every 3 months is promoting ‘resistance’ amongst the worm population. There are no new classes of wormer currently under development, so it is important that we update our thinking when it comes to best practice for worm control. Strategic worming uses worm egg counts to assess whether your horse actually needs worming.

Why is strategic worming and performing worm egg counts beneficial to your horse’s worm control programme?


  • Worm damage can cause poor performance, weight loss, diarrhoea and colic
  • 80% of worm burden sits in 20% of horses, meaning on average for every 5 horses grazing only 1 will require treatment. These are often young (under 4 years old) or old horses.
  • Strategic worming will save you money
  • Studies have shown 4 out of every 5 wormers are given unnecessarily
  • Over use of wormers actually reduces their effectiveness
  • A low level of worms can actually be beneficial to the immune system
  • Advice can be confusing and misleading without expert guidance

OVH Strategic Worming Package

To help owners manage their worming program, OVH Equine have put together an adult horse package for responsible equine parasite control. Our advice is to perform 4 faecal worm egg counts spread evenly over the course of a year to assess your horse’s worm burden. If the results are less than 200 eggs per gram, then there is no need to worm and the process should be repeated in 3 months time. If you have a result over 200 eggs per gram we will advise you of the appropriate product, based upon its active ingredient/drug.

How does it work?

  1. Complete a registration form and you will be provided with an annual worming pack with everything you need for 4 worm egg counts spaced evenly throughout the year (February, May, August and November).
  2. An email reminder will be sent at the start of each testing month and samples should be submitted by the last day of the month.
  3. Collect poo sample in glove provided (be sure to take a large pinch of faeces from 3 different areas in a pile of fresh faeces), invert glove and seal in bag 1 making sure to expel any air
  4. Collect an amount the size of a squash ball
  5. Complete details on sticker on bag 2 and place bag 1 inside
  6. Place the double bagged sample in freepost envelope provided and return to OVH immediately. Store the envelope in a fridge or cool place prior to posting
  7. Our laboratory expert Zoe Smith will email/phone results within 72 hours of receiving sample
  8. If the result shows your horse requires treatment Zoe will advise you of a suitable wormer to use based on responsible rotation of the active ingredient in the wormer. This can be dispatched via first class post.
  9. Approximately 2 weeks after treatment with the wormer we will send a re-test kit which should be completed as above and returned to us. This will enable us to check that the wormer has been effective

Please note – all horses under the age of 4 need worming regularly (even with low WEC) as younger animals are more prone to infection and can become sick more quickly. These younger horses are therefore not suitable for the package


The package will be charged at £80 per horse per year which will include:

  • 4 WEC test kits
  • 1 Re-test (if required)
  • 1 tapeworm wormer – all horses should be wormed for tapeworm once a year as these are not covered by a worm egg count. This will be dispatched at the start of November each year.
  • Advice from our lab team and vets at any time. Expert interpretation of results of WEC is crucial as a low level of worms can actually be beneficial to the health of your horse.

 Wormers required to treat high worm egg counts are not included. In addition we would also recommend an annual blood test to check for tapeworm which cannot be assessed from faecal samples.

What about young horses/foals?

All horses under the age of 4 require more frequent worming as they are more susceptible to infection. Please speak to one of our team for more advice about worming these horses.

How can I reduce my horse's worm exposure/burden? 

  • ‘Poo picking’ at least twice a week and ideally every day!
  • Avoid overstocking and overgrazing
  • Rotate fields where possible – ideally rotate with sheep/cattle
  • Immediately worm any new horses and keep them stabled for 48 hours to prevent worms being shed in fields
  • Try to keep young horses separate from older ones. Young horses often have the highest worm burden and as a result require worming more regularly
  • Worm mare approximately a month prior to foaling (seek advice as to which product is best)

Below is a guide to the wormers that are available, their active ingredient and what they can be used for:

Trade Name

Active Ingredient

Duration of action




13 weeks

Kills everything except tapeworm

Effective against encysted larvae

Can be used from 4 months of age

Can be used in pregnant mares

Equest Pramox

Moxidectin and praziquantel

13 weeks

Kills everything including tapeworm in a single dose

Can be used from 6 months of age

Can be used on pregnant mares



8 weeks

Kills all except tapeworm and encysted small redworm larvae

Strongid P


4-6 weeks

Double dose required to kill tapeworm

Can be used in foals from 4 weeks

Kills round worms

Does not kill bots or encysted small redworm larvae




Tapeworm only

Eqvalan Duo



Praziquantel and Ivermectin

8 weeks

Kills all in a single dose, except encysted small redworm larvae

Can be used from 2 months of age



4 weeks

5 day course kills encysted small redworm larvae

Does not kill tapeworm

Some evidence of resistance

Can be used on pregnant mares

Strategic Worming Registration Form
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