Deworming Program for Sheep and Goats: A Smarter Approach

A good deworming program for sheep and goats does not mean drenching the whole herd every few weeks. It means checking which animals actually carry heavy worm burdens (using faecal egg counts, eyelid colour and body condition), treating those animals with the right product chosen with your vet, weighing them so the label dose is correct, and recording every treatment. This approach protects growth and slows dewormer resistance.

Internal parasites are one of the most common hidden costs in small ruminant farming. Infected animals rarely die suddenly; they simply grow slower, give less milk and lose condition, month after month. And the old habit of treating everyone on a fixed calendar has made many worms resistant to the drugs that used to control them.

Know the enemy: main internal parasites

Different parasites cause different problems, and not every dewormer works against all of them. The main groups are:

• Barber's pole worm (Haemonchus contortus): a blood-sucking stomach worm, especially dangerous in warm and humid periods or irrigated pastures. Causes anaemia, weakness, bottle jaw (swelling under the jaw) and death in heavy cases.
• Other stomach and intestinal worms: cause diarrhoea, poor appetite and slow growth, mostly in young stock.
• Tapeworms: visible white segments in droppings; usually less harmful than breeders fear, except in heavy burdens in lambs.
• Liver fluke: in wet areas with snails (around canals, swamps and irrigated land). Causes weight loss, anaemia and liver damage.
• Coccidia: not worms but tiny parasites (protozoa) that cause diarrhoea in young lambs and kids in crowded, dirty pens. Normal dewormers do not treat them; your vet will advise.

Goats are generally more sensitive to worms than sheep and develop less immunity with age, so they often need closer monitoring.

Signs that an animal needs attention

Watch for:

1. Pale eyelids and gums (anaemia), the key sign of barber's pole worm.
2. Bottle jaw: soft swelling under the jaw.
3. Diarrhoea and dirty back ends (dags).
4. Weight loss or poor growth compared with herd mates on the same ration.
5. Rough, dull coat and weakness, lagging behind the group.
6. Sudden deaths in heavy Haemonchus infections, especially in young stock.

The FAMACHA method scores the colour of the inner lower eyelid from red (healthy) to almost white (severe anaemia). It was developed for barber's pole worm and helps decide which animals to treat. Ask your vet for training; scoring needs a little practice to be reliable.

Why blanket deworming backfires

Treating every animal on a fixed schedule seems safe, but it speeds up resistance. When all animals are treated, the only worms that survive are the resistant ones, and they become the next generation on the pasture. After a few years the dewormer no longer works.

A smarter program follows three principles:

• Test before you treat. Faecal egg counts (a simple lab test on a droppings sample) show whether a group really carries a heavy burden and which worm types are present.
• Treat selectively. Treat animals that show signs or high counts, and leave strong, healthy animals untreated when your vet agrees. These untreated animals keep a population of worms that are still sensitive to drugs.
• Check that the drug works. A faecal egg count before and after treatment shows whether the product is still effective on your farm.

Building your deworming program with the vet

There is no universal calendar, because worm risk depends on climate, rainfall, irrigation and grazing system. A dry desert farm feeding hay in pens has a very different risk from a herd grazing irrigated fodder or riverbanks after the rains. Work with your vet to set:

Never guess the weight. A lamb that weighs more than you think gets too little drug, which does not clear the worms and selects resistant ones. Never mix products yourself or use cattle products without veterinary advice, and always respect withdrawal periods before selling meat or milk.

Management that reduces worms without drugs

Drugs are only one tool. Management often does more:

• Clean feeding: use raised feeders and racks so feed is not contaminated by droppings.
• Pen hygiene: remove manure regularly and keep bedding dry, especially for young stock.
• Pasture rest and rotation where you graze, so larvae die off before animals return.
• Good nutrition: well-fed animals, especially with enough protein, cope better with worms. Pregnant and lactating females are more vulnerable around lambing; see our guide on feeding pregnant and lactating ewes.
• Cull chronic cases: animals that need repeated treatment year after year pass on their weakness. Consider them for culling.
• Quarantine new animals before they join the herd.

Keeping deworming records in practice

Selective treatment only works with records. You need to know which animals were treated, when, with which product, at what weight, and when the withdrawal period ends. Without that, you cannot tell resistant worms from a forgotten animal.

In Throf, each deworming is recorded as a treatment on the animal or group, with the product, date and notes, and the animal's weight history sits in the same file, which helps when calculating the dose with your vet. Reminders can be set for the next check, and the health history shows at a glance which animals keep needing treatment, the first candidates for culling. Selective treatment of external parasites follows the same logic; see our guide on ticks, mange and external parasites.

The short version

Do not drench everyone by the calendar. Check eyelids, condition and egg counts, treat the animals that need it with a product chosen with your vet, weigh before dosing, respect withdrawal periods and record every treatment. You will spend less on drugs and keep them working longer.