Sheep and Goat Parasites: Deworming Tips for Small Ruminants

Sheep and goat parasites, particularly gastrointestinal worms, are among the leading causes of stunted growth and reduced output in small ruminant herds. Diarrhea, weight loss, a dull coat, and dropping milk yield are subtle signs that often build up gradually, long before the farmer starts to worry. Understanding the life cycle of these parasites and adopting a well-planned deworming programme for sheep and goats helps protect the flock's health while avoiding drug resistance.

The main gastrointestinal worms in sheep and goats

Sheep and goats share most of their internal parasites, which is exactly why grazing them together on the same pasture speeds up transmission. Broadly speaking, we can distinguish:

• Gastrointestinal strongyles, roundworms that settle in the abomasum and intestine, causing diarrhea, loss of appetite, and anemia.
• The large liver fluke, a flatworm that thrives in wet areas thanks to an intermediate host (a small aquatic snail), damaging the liver and affecting output.
• Tapeworms (cestodes), generally less harmful but visible in droppings, which often worries farmers when seen in young animals.
• Coccidia, microscopic parasites that mainly affect young lambs and kids, triggering sometimes severe diarrhea around weaning time.

These parasites take advantage of wet spells and overcrowded pastures to multiply, with infective larvae surviving on the grass before being ingested by grazing animals.

Impact on growth and productivity

Even a moderate parasite burden directly hits the farm's economic performance:

• Slower growth in lambs and kids, delaying the age at which they reach slaughter weight.
• Lower milk production in lactating ewes and does.
• Reduced fertility and reproductive performance in cases of chronic infestation.
• A weakened immune system overall, leaving the animal more exposed to other diseases.

Young animals and females in late pregnancy or lactation are especially vulnerable, since their natural defenses are already stretched by growth or milk production.

Recognizing the signs of a parasitic infestation

Certain signs should alert the farmer and warrant a veterinary check-up:

• Persistent diarrhea, soiling around the hindquarters.
• Weight loss despite a normal appetite, or even loss of appetite.
• Pale mucous membranes (gums, conjunctiva), suggesting anemia.
• Dull coat or fleece, lacking its usual shine.
• Swelling under the jaw ("bottle jaw"), a sign often linked to a heavy parasite load.

These signs are not specific on their own: only a clinical exam, backed up if needed by a fecal analysis, can confirm the type and severity of the infestation.

Smart deworming strategies

Given the growing risk of parasite resistance to treatments, a goat or sheep dewormer should no longer be given routinely and without a clear plan. A few basic principles apply:

Tailor treatment to the situation

• Target the animals most at risk (young stock, pregnant or lactating females, thin animals) rather than automatically treating the whole flock.
• Rotate between different families of dewormers as recommended by your vet, to help limit the development of resistance.
• Stick strictly to the recommended dosage, weighing animals rather than guessing their weight by eye.

Manage grazing wisely

• Avoid overgrazing, which forces animals to graze close to the ground, where larvae concentrate the most.
• Rotate pastures to break the parasite's life cycle.
• Drain or improve wet and marshy areas, which favor liver fluke.
• Isolate and treat newly introduced animals before mixing them with the rest of the flock.

Boost the animals' natural resistance

• Provide a balanced diet along with clean, fresh water year-round.
• Avoid unnecessary stress (transport, overcrowding), which weakens the immune system.
• Regularly check the flock's body condition and mucous membranes.

An effective deworming plan is always best built with the help of a professional who can assess the actual parasite pressure on the farm, along with the season, local climate, and the flock's history. It's strongly recommended to consult vets experienced in sheep care or vets specialized in goat health to set up a protocol suited to each farm.

How often should you deworm your sheep and goats?

There's no universal schedule that fits every farm: it depends on the climate, the parasite load on the pasture, and the animals' condition. The best approach is to have the flock regularly assessed by a vet, who can recommend targeted treatment rather than a fixed calendar applied without any real assessment.

Need a professional opinion? If in doubt or in an emergency, find a veterinarian near you on TunisieVet.