How to keep your flock thriving and healthy

This spring has been benign compared to last year, but farmers still need to be vigilant about disease, writes Eamon O'Connell

Nematodirus is the biggest health risk to lambs as spring gives way to summer
Nematodirus is the biggest health risk to lambs as spring gives way to summer

Eamon O'Connell

What a difference a year makes. The weather is ideal, soil temperatures are on the rise and grass is becoming plentiful.

After a better than average lambing season on most farms with a decent crop of healthy lambs, ewes and lambs are now permanently out at pasture. The fodder shortage and the generally horrible spring of 2018 are a distant memory.

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However, we are still seeing levels of sickness in flocks. As I treated a lamb with pneumonia last week, the farmer said to me jokingly: "I wonder why I called you at all; sure a sick sheep is usually a dead sheep".

With morbidity so close to mortality in sheep, there are a number of areas to focus on to keep the flock healthy and thriving this spring.


This is a severe disease of lambs six to 12 weeks old and is characterised by diarrhoea, dehydration and weight loss. Lambs become infected by ingesting large numbers of larvae on contaminated pasture.

Nematodirus is different to other worms in that it takes almost a year for eggs to hatch, releasing infective larvae. When soil temperatures increase after cold weather, there is mass hatching of eggs.

The Department of Agriculture issued a nematodirus forecast which predicted peak hatching to occur in the last week of March on the south-west and west coast, and into the first two weeks of April for the rest of the country. This is up to three weeks earlier than last year.

This year, lambs should be already treated last week in the south west and west. Lambs in the rest of the country should be treated this week. Benzimidazoles (white drenches) are the treatment of choice.

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Prevention is achieved by keeping lambs off pasture that was grazed by lambs or calves or lambs last year. Twin lambs are more at risk as, due to the lesser availability of milk, they start to consume greater amounts of grass earlier.


This is a parasite that affects lambs three to eight weeks of age. Signs include a dark brown and often bloody scour. Coccidiosis, if not treated early, can result in irreparable damage to the lambs' digestive tract, leading to poor thrive and, often, a high mortality rate.

Like Nematodirus, keeping lambs away from previously grazed pasture is the best form of prevention.

The parasite survives in wet and muddy areas, so keeping the area around water troughs clean and regularly moving feed troughs to unpoached parts of paddocks are a great help. There are a number of products available to treat coccidiosis and it is best to consult with your vet as to which one to use.

Worm resistance

Resistance to some wormers is becoming more and more apparent on Irish sheep farms every year. It results in poor performance, morbidity and, in severe cases, high mortality. Great care needs to be taken when deciding what product to use and when to use it.

This will vary greatly between farms. Faecal sampling at appropriate times will determine what product to use and if the product already used is effective.

Simply buying a product based on price or convenience is no longer acceptable, and some would argue that this type of decision making is what greatly contributed to the development of resistance in the first place.

A dosing plan should be made in conjunction with your vet. It helps to have a month by month plan, detailing when faecal samples should be taken. Based on this, an appropriate worming strategy can be devised. Dosing plans should not be rigid - changes may have to be made depending on grass availability and weather conditions throughout the year.

Clostridial diseases

These include blackleg, pulpy kidney, braxy, lamb dysentery and tetanus. The diseases are a serious threat to lambs, resulting in death within a few hours. Vaccination is very effective and quite inexpensive. Two injections, separated by four to six weeks are required for full immunity. Pasteurella and clostridia combination vaccines are also available. Before buying a vaccine, again have a chat with your vet. A plan should be formulated based on what vaccine to use and when to use it.

If a vaccine requires a booster shot according to manufactures specifications, then full immunity will not be achieved unless both shots are given. Only one shot is most probably a waste of time, energy and money.

Flock Health Plan

This should be the cornerstone of every sheep farm. You should sit down with your vet and carry out a full review of your farm over the past year.

Areas for improvement should be identified, targets should be set and a plan put in place to achieve these targets. The more records you keep, the better a picture you can get of how your flock is performing and the easier it will be to identify areas for improvement.

Hopefully the spring will continue to be a good one, and with a cautiously optimistic outlook regarding lamb prices, things look hopeful. The lamb with pneumonia that I treated thankfully made a full recovery. A sick sheep may not be a dead sheep after all.

Eamon O'Connell is a vet with the Summerhill Veterinary Clinic, Nenagh, Co Tipperary.

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