Intestinal Parasites Are a Serious Problem for Small Ruminants – Vet Insights 2025 🐑🐐

By Dr Duncan Houston

Revised: 2025

Plain‑text summary (160 characters):

Barber pole worms devastate sheep/goats. Vet‑recommended FAMACHA scoring, targeted dewormer use, and pasture management fight resistance. 🐑🐐

Introduction

In 2025, small‑ruminant farmers and veterinarians alike are still battling one of the most persistent challenges in sheep and goat health: intestinal parasites. Among these, the notorious barber pole worm (Haemonchus contortus) remains particularly devastating. Left unchecked, it causes severe anemia, edema, poor growth, and even death in small ruminants—leading to substantial economic losses on farms worldwide. In this comprehensive article, Dr Duncan Houston explores why intestinal parasites remain a “silent threat,” how resistance to dewormers complicates control, and outlines practical, evidence‑based solutions that producers can implement today.

📌 Why This Matters Now (in 2025)

• Evolving parasite resistance: Barber pole worms have developed resistance to multiple drugs, making old routines ineffective.
• Greater awareness: Producers are now more informed—but often overwhelmed—by conflicting advice.
• Climate change factor: Warmer winters allow parasites to survive year‑round in many regions.
• Animal welfare and profit: Healthy animals mean better flock performance, less labor, and higher revenue.

The Barber Pole Worm: A Formidable Foe 🪱

Haemonchus contortus, commonly known as the barber pole worm, is a blood‑feeding parasite that resides in the abomasum (the true stomach) of sheep and goats. Its striking name comes from the alternating red (blood) and white (reproductive tissues) stripes visible in adult worms. But what makes them a true adversary in 2025? Here's why:

Anemia & “Bottle Jaw”

Adult worms feed on blood. Heavy infections cause anemia—identified by pale mucous membranes. Severe cases lead to submandibular edema, famously known as “bottle jaw.”

Rapid Life Cycle

• Females produce thousands of eggs daily.
• Eggs develop to infective larvae (L3) in days under ideal temperatures.
• They remain viable on pasture for months.

High Morbidity and Mortality

In high‑density grazing settings—especially during humid, warm seasons—entire groups can succumb rapidly. Death can occur within days of noticeable anemia or sudden weakness.

Drug Resistance: A Growing Challenge

Dewormer resistance is perhaps the most serious complication today. It occurs when parasite populations survive treatment and pass resistant genes to the next generation. Common issues in 2025 include:

• Multiple‑drug resistance: Barber pole worms resistant to benzimidazoles, macrocyclic lactones, and imidazothiazoles.
• Frequent use backfires: Routine deworming without targeting promotes resistance.
• Sub‑therapeutic dosing: Incorrect weights or miscalculations reduce drug efficacy.

Studies show that even farms using rotational deworming are experiencing less than 95% egg‑count reduction—indicating true resistance.

FAMACHA® Scoring: Targeted Deworming for the Win

The FAMACHA system is a selective deworming tool that helps keep animals healthy while slowing resistance:

How It Works

1. Examine the inner eyelid coloration using a FAMACHA card.
2. Assign scores from 1 (pink, healthy) to 5 (pale, severely anemic).
3. Treat animals scoring 4 or 5.

This method ensures treatment targets only the most affected animals, preserving refugia—populations of parasites unexposed to drugs—crucial in slowing resistance.

Best Practices with FAMACHA

• Score at least monthly during high-risk seasons.
• Record each animal’s ID and score.
• Pair FAMACHA with body-condition scoring and growth tracking.
• Combine with pasture management and strategic deworming.

Integrated Parasite Management (IPM): Holistic Control

IPM recognizes that no single method is sufficient. It combines:

Pasture Rotation

• Resting pastures for >3 months lets L3 larvae die off.
• Using multi-species grazing (e.g., cattle or horses) breaks parasite cycles.

Feed & Nutrition

• Balanced minerals and protein boost immunity.
• Tannin-rich forages (e.g., chicory, birdsfoot trefoil) show some anti-parasitic effects.

Breeding for Resistance

• Selecting genetically resistant animals for breeding reduces parasite load over time.
• Breeds like Katahdin and St. Croix often perform better under parasite challenge.

Biological Controls

• Dewormer-resistant fungi (e.g., Duddingtonia flagrans) feed on larvae in feces.
• Offer as feed supplement to livestock.
• Results can reduce pasture contamination by up to 50%.

Proper Dewormer Use

• Use drugs only when needed, guided by FAMACHA or fecal egg counts.
• Ensure accurate dosing based on weight.
• Rotate drug classes judiciously; avoid frequent switches.
• Maintain refugia by leaving healthy animals untreated.

Monitoring: The Cornerstone of Success

Fecal Egg Count (FEC)

• Collect fecal samples regularly for lab analysis.
• Perform FECRT—fecal egg count reduction test—to evaluate drug efficacy.

Health Observations

• Track weight, body condition, FAMACHA scores, and production data.
• Note weakness, bottle jaw, lethargy, poor appetite, or low growth.

Record Keeping

• Record treatments, results, dewormer brand, dosage, and weights.
• Archive FAMACHA readings, pasture rotations, and performance data.

Real-World Example: Prevention in Practice

On a 100-head sheep farm in 2025:

• Monthly FAMACHA scoring identifies 5–7% of animals needing deworming—reduced from 30% the previous year.
• Pastures are rested for 120 days; alternating goats and sheep helps sustain low larvae levels.
• Animals are sequenced with resistant breeds; overall FECs have fallen by 60% year-over-year.
• Dewormers are used only 2–3 times per year—with documented 95–99% egg-count reduction.

Summary: 5 Keys to Parasite Control in 2025

Frequently Asked Questions

1. How often should I FAMACHA‑score?

During parasite season (spring/fall), score every 2–4 weeks. In low-risk months, you can reduce frequency—but continue monitoring for signs.

2. Can all dewormers still work?

If FECRT shows adequate egg‑count reduction with a drug class, continue its use. If not, switch classes or consult your veterinarian for alternatives.

3. Should I use combination dewormers?

Only under veterinary guidance and after confirming resistance to a single class. Misuse can accelerate resistance development.

4. How important are genetics?

Very. Even selecting a few resistant individuals yearly can significantly reduce overall flock parasite load over time.

5. Is pasture rotation essential?

Yes. No drug alone can match the effectiveness of well-planned pasture rest in breaking parasite cycles.

Conclusion

In 2025, intestinal parasites remain a major threat to the health and profitability of small-ruminant operations. The barber pole worm poses a particularly high risk due to rapid reproduction, severe clinical signs, and growing drug resistance. However, fully integrated approaches—targeted deworming (using FAMACHA), strategic pasture use, prudent dewormer choices, improved nutrition, and vigilant monitoring—offer effective solutions.

Working with your veterinarian—and backing interventions with data—you can protect your flock, maintain animal welfare, and control costs. With thoughtful management, parasites no longer need to be a silent threat. Instead, they can be a manageable part of sustainable livestock production.

Dr Duncan Houston