Cyathostomins
Small Strongyles
- Australia's most common equine internal parasite.
- Can cause weight loss, diarrhoea and poor performance.
- Encysted larvae burrow into the gut wall and are not detected on routine faecal egg counts.
Strongylus spp.
Large Strongyles
- Much less common today thanks to modern parasite control.
- Historically serious — larvae can damage the blood vessels supplying the intestines.
- Good parasite management and regular monitoring have greatly reduced their prevalence.
Ascarids · Parascaris spp.
Roundworms
- Mainly affect foals, weanlings and young horses under two.
- Can cause coughing, poor growth, a pot-bellied appearance and, in heavy burdens, intestinal blockages.
- Adult horses usually develop immunity and are rarely affected.
Oxyuris equi
Pinworms
- Cause intense itching around the tail base and hindquarters.
- Often not detected by faecal egg counts — eggs are laid around the anus, not passed in manure.
- Diagnosis usually requires a tape test around the perineum.
Anoplocephala perfoliata
Tapeworms
- Not reliably detected on routine faecal egg counts — eggs are shed intermittently in segments.
- Seasonal treatment may still be recommended, particularly in autumn.
- Can contribute to certain types of colic, especially at the ileocaecal junction.
Gasterophilus spp.
Bots
- Adult bot flies lay tiny yellow eggs on the horse's coat, especially the legs and shoulders.
- Larvae are ingested and overwinter attached to the stomach lining.
- Not detected on faecal egg counts.
- Usually managed with a seasonal boticide treatment after the first frost.
The point of testing
Why faecal egg counts matter
Faecal egg counts tell you which horses in your herd are actually shedding worm eggs — and roughly how many. That means you can target treatment at the horses that need it, instead of worming everyone on the same schedule regardless of their burden.
Targeted parasite control has three big benefits:
- Slows resistance. Every unnecessary worming dose selects for resistant parasites. Worming only when needed keeps existing chemicals working for longer.
- Avoids unnecessary chemicals. Many adult horses shed very few eggs and simply don't need routine worming. Testing proves it.
- Catches problems early. Rising counts, unexpected shedders and treatment failures show up in the numbers long before they show up in the horse.
A faecal egg count is a powerful tool, but it doesn't detect every parasite. Tapeworms, bots, pinworms and encysted small strongyle larvae need different strategies — WormScope factors this into every report.