💊 Vet Guide: New Deworming Recommendations for Horses | 2025 Parasite Control & Resistance Prevention Tips 🐴

By Dr Duncan Houston, BVSc

It’s time to rethink how we deworm our horses. For decades, horses were dewormed every **1–2 months** as a routine practice—but new research shows this old approach may do more harm than good. It doesn’t just waste money—it fuels **parasite resistance** that can make drugs useless. 🧠🦠

In this 2025 guide, I’ll explain the latest research on equine parasite control, why fecal egg counts are critical, and how **strategic deworming** can keep horses healthier—and medications effective longer. 💡🧪

🧠 The Problem with Calendar-Based Deworming

For years, horse owners followed a calendar: deworm every 2–3 months, like clockwork. But this method deworms all horses—**even those that don’t need it**. The result? Parasites develop resistance much faster. ⚠️📉

New Research Insights:

• 🧪 Horses dewormed **4–6 times per year** showed parasites that rebounded **twice as fast**
• 📈 Resistance to moxidectin and ivermectin developed rapidly
• 📉 Total drug effectiveness declined across entire herds

Instead of killing worms, we’re breeding super-worms that current drugs can’t stop. ❌🧬

📊 Study Results from Europe

A multi-year study led by Dr. Thomas Geurden of Zoetis followed two draft horse farms in Belgium practicing traditional deworming. Horses were treated:

• 💊 4x/year with **moxidectin**
• 💊 6x/year with **ivermectin**

The results showed that **parasite eggs reappeared far sooner** than expected—a clear sign of growing resistance. 🦠⏱️

What They Did Next:

• 🔬 Ran **fecal egg counts** every two weeks (April–September)
• 📉 Only horses with **high egg counts** were dewormed
• 📆 All others received **just two treatments per year**

This strategic approach reduced total deworming by **one-third** and slowed drug resistance by **up to 300%**. 💥

🧪 What Is a Fecal Egg Count?

A **fecal egg count (FEC)** measures the number of parasite eggs in a horse’s manure. It identifies horses that are “high shedders” vs. those with low or no egg output. 📉💩

Why It Matters:

• ✅ Only deworms horses that truly need it
• 📉 Reduces unnecessary drug use
• 🧬 Slows development of resistance
• 💰 Saves money on unnecessary treatments

FECs are affordable, quick, and available through most equine vets. They’re now considered **the gold standard** for modern parasite control. 🧪📋

🐴 Younger Horses May Still Need More

The study showed that **younger horses** often needed **3 dewormings per year**, due to immature immune systems. That’s okay—as long as treatments are still based on egg counts, not arbitrary schedules. 📅

✅ Deworming Strategy for 2025

🧠 Step-by-Step Guide:

• 📋 Perform a fecal egg count **every 3–6 months**
• 💩 Deworm only horses with **moderate or high egg counts**
• 🧾 Log each horse’s response and shedding status
• 🧬 Rotate dewormers only when needed—not just by habit
• 🩺 Partner with your vet to tailor a plan for your farm

It’s not about deworming less—it’s about **deworming smarter**. 🧠✅

⚠️ Warning Signs of Resistance

Resistance may be developing if:

• 🐴 Parasite eggs return quickly after treatment
• 💉 You’ve used the same dewormer repeatedly without testing
• 📉 Drug efficacy drops with each use

Resistance is a growing problem worldwide—don’t wait until your dewormer stops working. ❌🦠

📲 Use Ask A Vet for Deworming Plans

The Ask A Vet app simplifies parasite control with science-based strategies:

• 📋 Schedule and track fecal egg counts
• 📱 Chat with a vet about drug selection and rotation
• 📊 Record treatment response by individual horse
• 📉 Learn how to reduce resistance risk on your farm

Ditch the guesswork—get personalized parasite management for your herd. 🐴📲

✅ Deworming Takeaways for 2025

• 💊 Routine deworming every 1–2 months causes drug resistance
• 🧪 Fecal egg counts are essential for targeted treatment
• 📉 Strategic deworming reduces total drug use and improves outcomes
• 🧬 Resistance can develop quickly—especially with ivermectin and moxidectin
• 📱 Use Ask A Vet to build a custom parasite control plan

📲 Final Thoughts from Dr Duncan Houston

Old habits die hard—but when it comes to parasite control, doing less is often doing more. Fewer, smarter dewormings protect your horse and preserve the effectiveness of life-saving medications. 🧠💙

Download the Ask A Vet app to get expert help interpreting fecal egg counts, rotating dewormers, and building a resistance-free plan for 2025 and beyond. 🐎📱