Rainy season alert: Internal parasites (worms) in goats and sheep

This small stock management advisory is kindly shared by Bulembe Farm, Matabeleland. Feature photo credit to Klipspringer Ranch.

The rainy season creates ideal conditions for internal parasites (worms). If not properly managed, worms can seriously affect the health, productivity, and survival of goats and sheep—especially young animals.

Why worm problems increase during the rainy season

Worms thrive in warm, wet conditions. Moisture allows worm eggs and larvae to survive longer on pasture, increasing contamination levels. During the rainy season, grazing animals are therefore exposed to a much higher risk of infection.

How worms spread

Goats and sheep pass worm eggs in their droppings.
When conditions are wet, these eggs hatch into larvae that climb onto grass and soil surfaces, contaminating grazing areas.

How animals become infected

While grazing, goats and sheep ingest worm larvae from contaminated grass or soil. The more heavily stocked or poorly managed the pasture, the greater the risk of infection.

Effects of worms on animal health

Heavy worm infestations can cause:

• Anaemia, especially from blood-sucking worms such as Haemonchus
• Weight loss and poor body condition
• Dull hair or wool coat
• Reduced growth and production
• Weakness and poor appetite
• Death in severe cases, particularly in kids and lambs

Early detection is critical, as animals may look normal until worm burdens are already high.

Treatment of worms

Worms are treated using dewormers (anthelmintics).
However, incorrect dosing or frequent, unnecessary use can lead to dewormer resistance, where treatments no longer work. This is a growing and serious problem.

Importance of worm load testing

Before treating, it is strongly recommended to consult a veterinarian or animal health technician to:

• Perform a faecal egg count (worm load test)
• Identify the type and severity of worm infestation
• Recommend the correct dewormer and dosage

Targeted treatment ensures better results and helps slow the development of resistance.

Using the FAMACHA system

The FAMACHA chart is a practical tool used to assess anaemia by checking the colour of the lower eyelid.
It helps farmers:

• Identify animals that actually need treatment
• Reduce unnecessary deworming
• Save money
• Protect the long-term effectiveness of dewormers

FAMACHA is especially useful for managing blood-sucking worms during the rainy season.

Additional prevention tips (very important)

Good management reduces worm pressure:

• Avoid overstocking grazing areas
• Rotate pastures where possible
• Keep feeding and watering areas clean and dry
• Provide good nutrition to strengthen immunity
• Quarantine and check new animals before mixing them with the herd

Worm control during the rainy season requires awareness, testing, and good management. By combining pasture management, targeted treatment, and simple monitoring tools like FAMACHA, farmers can protect their goats and sheep from serious losses and maintain healthy, productive herds.

What is FAMACHA?

FAMACHA is a simple, hands-on system used to check anaemia in goats and sheep, mainly caused by the blood-sucking worm Haemonchus contortus (the barber-pole worm).

It works by examining the colour of the lower eyelid and comparing it to a colour chart. Pale eyelids indicate anaemia and a high worm burden.