Why are faecal egg counts important?

For many years horses were dewormed on a fixed schedule, the same for every horse. We now know this can be unnecessary and even harmful. Overuse of dewormers leads to resistance, which reduces their effectiveness.

A faecal egg count assesses the type of infection and measures the number of eggs per gram of faeces (EPG). If the result is high, usually above 200 EPG, targeted deworming of positive horses is recommended. Two weeks after treatment a repeat test can show the reduction in egg count. This can reveal possible resistance to a dewormer.

Faecal testing is most important in spring and summer. Testing in autumn or winter can be negative because some worm species go dormant and shed no eggs. That does not mean there are no worms present.

Faecal testing cannot detect all parasites or life stages. It mainly targets redworms, large strongyles and roundworms. This is why the advice is to still deworm horses systematically at least once a year.

The general advice is now:

• Three times per year a faecal egg count in horses older than three years, namely in March, June and September, before the outside temperature drops and worms go dormant.
• Once per year in autumn, October or November, a routine deworming with a product that also covers tapeworms.

Youngstock operations require a different deworming policy.

There is no one standard deworming schedule. Each horse should be assessed individually and a deworming policy set by your vet, based on the horse’s age and health and on stable and pasture management. The goal of deworming is to keep the infection pressure from the pasture as low as possible.

Deworming horses under 3 years of age

For horses under three years the advice is to perform faecal testing more often than the three times per year mentioned above. Another option is to follow a fixed deworming schedule, because their immunity is limited and these horses can become much sicker from worm infections. Deworm all horses from the same group or pasture at the same time with the correct dose.

Deworming foals

Foals must also be protected against roundworms. The required active is pyrantel. There is resistance of roundworms to some commonly used dewormers. Not every product is suitable for foals, so ask your vet.

Deworming pregnant mares

The advice is to deworm a pregnant mare one to two weeks before foaling with ivermectin. This helps protect the newborn foal. It is also important that the mare is stabled before foaling in a mucked out and thoroughly cleaned box.

Selective deworming after the grazing season

As mentioned, it is still recommended to perform a comprehensive deworming once a year, around October or November at the end of the grazing season when most horses return to the stable. Deworm broadly at that time, not only against large and small strongyles and roundworms, but also against tapeworms and bot larvae.

The importance of good pasture management

Alongside faecal testing, pasture management is crucial to prevent worm infections. Practical tips:

• Remove droppings daily from paddocks and at least twice weekly from pasture.
• Avoid overgrazing. Too many horses on a small field raise infection pressure.
• Rotate fields regularly, ideally every two to three weeks, using clean paddocks where possible.
• Graze pastures alternately with other species such as sheep and cattle. They do not get sick from horse worms but ingest the larvae and lower infection pressure. Mowing is an alternative.
• Do a faecal test before moving to a new field so that heavily shedding horses are treated first.
• Test and, if needed, deworm newly arrived horses before turnout.

With good management you can reduce the need for deworming and help prevent resistance. Does your horse have too many worms after a faecal test? Review your pasture management.

Supplements and support

While dewormers remain necessary with confirmed infection, you can support your horse’s resilience and gut health with natural supplements, such as:

• PUUR Parasitus: Natural support for the intestinal environment with herbs.
• Verm X: An herbal preparation available as nuggets, powder or liquid to support healthy gut function.

Note: natural products can be supportive, but they do not replace regular deworming with a proven infection.

Do you have questions about deworming and faecal testing in horses? Contact us at veterinarian@vetsend.co.uk.