The Top Five Sheep & Goat Parasites and How to Control Them Effectively

The Top Five Sheep & Goat Parasites and How to Control Them Effectively

You notice one of your animals hanging back from the flock or herd. Her coat is looking dull and her energy is noticeably lower than usual. On checking her lower eyelid you see the normally pink colour has faded to pale white. These subtle changes often signal a parasitic infestation that, left unchecked, can devastate individual animals and entire flocks or herds.

Internal and external parasites can cause anaemia, weight loss and reduced productivity in both sheep and goats. Identifying the most common culprits- such as barber’s-pole worms and coccidia- and implementing rotational grazing and targeted treatment protects flock and herd health year-round.

At The Vale Veterinary Group, our team understands the unique challenges faced by sheep and goat keepers across Devon. With our comprehensive diagnostic services and expertise in farm-animal health, we work with smallholders and commercial producers to develop targeted parasite-control strategies that protect productivity and profitability all year.

Why Parasite Control Matters for Your Sheep & Goat Flock

The Hidden Threat to Flock/Herd Health

Parasites represent one of the most significant health challenges in sheep and goat management- even before we see obvious symptoms. These organisms steal vital nutrients, compromise immune function and create cascading health problems that affect everything from growth rates to reproductive success.

The economic impact extends beyond treatment costs. Parasitised animals convert feed less efficiently, produce less (wool, milk or meat), experience reduced fertility and require more intensive management. In severe cases- particularly with blood-feeding parasites- infestations can prove fatal within days.

Regular farm visits allow our veterinary team to detect parasitic infections early, when intervention is most effective and least costly. Body-condition scoring, mucous membrane evaluation and faecal testing help reveal problems before they compromise productivity.

Dispelling Common Parasite Myths

Many keepers believe only visibly sick animals carry parasites- but healthy-looking sheep or goats often harbour significant worm burdens. Some animals show few outward signs despite heavy infestations, while simultaneously contaminating pasture and increasing risk for more vulnerable animals.

Another dangerous misconception is that regular blanket treatment alone solves parasite problems. Over-reliance on chemical treatments has created widespread dewormer resistance. In the UK, the Sustainable Control of Parasites in Sheep (SCOPS) guidelines emphasise sustainable and integrated control of parasites.

Effective parasite control requires an integrated management strategy combining strategic grazing, selective treatment based on need, and regular monitoring (e.g., faecal egg counts). This approach slows resistance development while maintaining treatment efficacy for animals that truly need it.

The Five Most Common Parasites Threatening Your Sheep & Goat Flock

1. Barber’s Pole Worm: The Blood-Feeding Killer

The worm Haemonchus contortus is one of the most dangerous internal parasites affecting small ruminants (sheep and goats). These blood-sucking worms attach to the stomach lining and consume so much blood that severe anaemia develops rapidly.

Key characteristics include:

• Pale or white mucous membranes in eyes and gums
• “Bottle jaw” (fluid accumulation under the chin)
• Sudden weakness or collapse in previously healthy animals
• Rapid death in heavily parasitised stock

Barber’s pole worm thrives in warm, humid conditions- which in the UK means wet pasture conditions, particularly in the southwest (Devon) and during warmer seasons. The FAMACHA scoring system (which evaluates eyelid colour) provides a practical field tool for targeting which animals need treatment without drenching the entire flock or herd.

2. Coccidia: The Young Lamb or Kid’s Challenge

Eimeria spp. are microscopic parasites that primarily threaten lambs and kids- typically from around three weeks to five months of age. These organisms damage the intestinal lining, causing severe diarrhoea, dehydration and stunted growth during critical development periods.

Unlike many worms, coccidia spread through contaminated environments rather than pasture grazing alone. Overcrowded housing, wet bedding and shared feeding areas create ideal transmission conditions. Prevention focuses on environmental management– clean, dry housing, elevated feeding areas and prompt removal of soiled bedding dramatically reduce infection pressure.

3. Liver Fluke: The Silent Liver Destroyer

Fasciola hepatica infection develops slowly, with parasites migrating through liver tissue and causing progressive damage over months. Affected animals show gradual weight loss, poor coat quality and reduced productivity despite adequate nutrition.

These parasites require specific intermediate hosts- mud snails (especially Galba truncatula)- to complete their life cycle. Sheep or goats grazing near ponds, streams, marshy areas or poorly drained pastures face the highest risk. Unlike many worm parasites, liver fluke cannot be controlled through pasture rotation alone.

Prevention requires managing water sources and drainage. Fencing animals away from wet areas, improving pasture drainage and strategic use of appropriate flukicides protect stock in fluke-endemic regions like Devon.

4. Lungworms: The Respiratory Threat

Dictyocaulus filaria (and related species) cause respiratory disease characterised by chronic coughing, laboured breathing and exercise intolerance. These parasites develop in the lungs and airways, triggering inflammation and secondary bacterial infections.

The lungworm lifecycle involves intermediate hosts including slugs and snails. Animals become infected by accidentally ingesting these carriers while grazing. Young animals and those with compromised immunity show the most severe symptoms. Diagnosis requires specific testing, as lungworm eggs appear intermittently in faeces and are easily missed with standard faecal examinations.

5. External Parasites: Lice, Mites, Ticks (and Sheep Scab)

External parasites such as lice, mites and ticks cause intense irritation, skin damage and disease transmission. Lice infestations lead to constant scratching, hair loss and reduced productivity. Mites burrow into the skin, creating scabs, thickened skin and secondary infections that spread rapidly through flocks or herds.

Ticks (e.g., Ixodes ricinus) pose dual threats- direct blood loss from feeding and transmission of serious diseases. Heavy tick burdens can cause anaemia similar to internal parasites, while tick-borne illnesses create additional health challenges.

In sheep, the condition known as Sheep Scab is of special importance in the UK- a notifiable disease requiring veterinary involvement.

External parasite control requires different approaches than internal parasites. Regular inspection, appropriate topical treatments, environmental management and quarantine of new stock all play roles in keeping these pests under control. Our farm services include full parasite management planning for both internal and external threats.

Building an Effective Parasite-Management Strategy

Integrated Control: Beyond the Drench Gun

Successful parasite control in sheep and goats requires multiple complementary strategies working together. Relying solely on chemical treatments accelerates resistance while failing to address pasture contamination and reinfection. The SCOPS guidelines emphasise this integrated, sustainable approach.

Key components include:

• Body-condition scoring, FAMACHA evaluation and selective treatment rather than blanket drenching
• Supporting natural immunity through balanced nutrition, appropriate mineral supplementation and reduction of stress
• Maintaining ‘refugia’ (untreated animals) to slow resistance development

Strategic Grazing for Parasite Reduction

Grazing management represents one of the most powerful tools for reducing parasite pressure without chemical treatment. Rotational grazing interrupts parasite life-cycles by moving animals before infective larvae reach peak numbers on pasture.

Multi-species grazing (e.g., sheep with cattle) reduces parasite loads because many small-ruminant parasites cannot complete development in cattle. These animals act as biological “vacuum cleaners,” consuming infective larvae without becoming infected themselves.

Maintaining appropriate stocking rates prevents over-grazing and reduces the concentration of parasite eggs on pasture. Animals forced to graze close to the ground ingest more infective larvae; those with access to adequate forage can selectively graze higher, cleaner vegetation.

Our team at The Vale provides guidance on implementing effective grazing strategies suited to your property size, pasture quality and flock/herd size.

Veterinary Diagnostics: Knowledge-Based Treatment

Faecal-egg-count (FEC) testing reveals which animals carry significant parasite burdens and whether treatments are working. Regular monitoring detects resistance development early, allowing you to adjust protocols before failure becomes widespread.

Blood testing assesses anaemia severity and overall health status, helping distinguish parasitic disease from other conditions with similar signs. Physical examinations by our experienced veterinary team identify subtle changes that owners may miss. Regular flock/herd-health reviews ensure your parasite-control programme aligns with seasonal risks, pasture conditions and individual animal needs.

Protecting Your Investment Through Proactive Parasite Management

Understanding the specific parasites threatening your sheep and goats empowers you to implement targeted, effective control measures. Early recognition of clinical signs, strategic use of diagnostics and integrated management approaches protect both animal welfare and productivity.

At The Vale Veterinary Group, we partner with sheep and goat producers to develop customised parasite-control programmes based on your specific circumstances, pasture type and production goals. Our team’s expertise in farm-animal health, combined with our diagnostic capabilities, ensures your flock or herd receives the expert care it deserves.

Whether you are managing a small hobby flock or a commercial operation, proactive parasite control safeguards your investment and keeps your animals healthy and productive. Contact our team today to schedule a flock/herd-health consultation and develop a parasite-control strategy tailored to your operation.