Coccidiosis – Are your lambs at risk?

June 2, 2025

Lambs between 3 to 4 weeks old may be at risk of coccidiosis – a common but serious disease affecting young lambs on many farms. Here’s a quick guide to help you spot the signs and protect your flock.

Quick Facts About Coccidiosis
Coccidiosis is caused by a protozoal parasite that multiplies in the gut lining. It’s a disease of young lambs, particularly when they’re under stress or exposed to a high challenge before they’ve had chance to develop immunity.
· No cross-infection between cattle and sheep (they have different species of coccidia)
· Lambs aged 3–8 weeks are most at risk
· Immunity builds over time – disease strikes when exposure is high before immunity develops or eggs can be seen on faecal egg count
· Lambs are more vulnerable if:
• Their immune system is under pressure
• They’ve had poor nutrition
• They’re fighting other gut worms (e.g. nematodirus)
• Weather is cold, wet or muddy

What Does Coccidiosis Look Like?
Be alert for:
· Lambs looking tucked up or listless
· Poor fleece quality
· Weight loss / failure to thrive
· Diarrhoea (often with mucous and blood-stained)
· Straining to pass faeces
· Sudden death or progressive deterioration in heavily infected lambs
➡️ Even if lambs survive, gut damage can lead to long-term growth issues.

Where Does Infection Come From?
Lambs pick up coccidial oocysts (eggs) from contaminated pasture or bedding. These oocysts are shed in the dung of older lambs or carrier ewes.
Key risk areas include:
• Wet, muddy ground – around creep feeders, field shelters, troughs
• High-stock density – where infection builds up over time
• Paddocks near buildings – especially where young lambs are repeatedly grazed
Oocysts are hardy – they can survive in the environment for months, even through winter and some disinfectants.

Managing the Risk
The goal is to build immunity without causing disease – which can be a fine balance.
· Lambs need some exposure to develop immunity – but not so much they get sick
· Hygiene is key – clean troughs, gates, bedding and kit regularly
· Avoid high stocking rates and heavily contaminated pastures
· Watch for lambs going onto “high-risk” ground with little previous exposure

Treatment – Plan it Right
Treatment can be effective, but timing is critical.
Please give us a call if you would like to discuss when and how to treat – we may recommend:
• Speciation testing to identify if the disease-causing strains are present
• Strategic treatment for at-risk age groups (especially if you have a range of lambing dates)
• Follow-up doses if the challenge is high or lamb ages vary widely
• Advice on products like toltrazuril or diclazuril (timing and correct use matter)

Once coccidia are on your farm, they’re likely to stick around – but good planning and hygiene can reduce the risk year on year. Talk to us if you have any concerns around coccidiosis and we can plan appropriately for your next flock health plan. This way we can ensure maximal protection and growth in your lambs.