Spring Worming: Staying Ahead of the Lifecycle in Australia

By mikaela constanti
2 min read

Spring is the most critical season for parasite control. As temperatures rise and pasture growth increases, worm lifecycles accelerate — and pasture contamination can build quickly if not managed strategically.

What Happens in Spring?

When temperatures reach around 15–25°C, eggs passed in manure can develop into infective larvae in as little as five days. The full lifecycle takes approximately 5–6 weeks.

This means multiple lifecycles can occur between August and December. With each cycle, more larvae accumulate on pasture, increasing the number of infective larvae your horses ingest.

While adult horses develop some immunity, high larval exposure can still increase worm burdens, particularly in young or stressed horses.

Practical Spring Strategies

1. FEC All Horses

Test every horse at the start of spring to identify:

  • High shedders
  • Low shedders
  • Overall paddock contamination risk
2. Deworm According to FEC Results

Treat only horses with elevated egg counts.
Targeted treatment reduces egg shedding, preserves refugia, and slows resistance.

3. Conduct a FECRT

Perform a Faecal Egg Count Reduction Test (FECRT) 10–14 days after treatment to confirm:

  • The chosen wormer is effective
  • There is no developing resistance
  • Your program is working as intended
4. Manage the Pasture

Spring management is just as important as treatment:

  • Remove manure regularly
  • Avoid overstocking
  • Rest paddocks where possible
  • Consider cross-grazing with cattle or sheep

Reducing manure limits infective larvae, lowering worm exposure.

Who Needs Closer Monitoring?
  • Foals and yearlings
  • Pregnant mares
  • High-performance horses
  • Horses on high-density properties

Bottom Line

Spring is when worm numbers can escalate quickly. Strategic FEC testing, targeted deworming, FECRT (Faecal Egg Count Retest) confirmation, and strong pasture management help prevent larval build-up that will otherwise impact horses later in autumn and winter.

Final Thought

Spring worming isn’t about treating more; it’s about staying ahead of the lifecycle. Test, treat smartly, confirm effectiveness, and manage the pasture to protect your horses for the seasons ahead.