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Prepare now to dodge the worst of disease threat

The sheds are empty and the sheep are out on pasture. It's the strength of our sheep industry that the vast majority of the sheep's life is spent outdoors. This is extensive farming as opposed to the other forms of intensive food production.

Outdoors usually means less diseases, with the exception of a few. Let's cover three of these this week:

  • Liver fluke -- It is early in the season to be talking about fluke, but now is the time to prepare to dodge the worst of this disease. There will be over-wintering stages of the parasite on the pasture as we speak. Spring-grazing flocks will slowly increase that number and as the season rolls on, we see overwhelming levels affecting the livers of all the flock. But just like weeds in the garden, if we get out early with the spray we stop the spread and complete choking of the pathways with weeds. And so it goes with fluke.

Identify the fields that were troublesome last year and use a flukecide that kills immature stages of the parasite on the grazing stock that graze that ground.

You will need veterinary advice on this issue and one of the best ways to save time and money is to get accurate advice at the outset. To finish on fluke, the reason we are so anxious about this parasite is that there is an emerging resistance problem and existing medicines are therefore less effective.

Fluke is also worrying in that the early migrating fluke does untold damage to the young livers of our lambs in the space of a few short weeks. These migrating fluke larvae can then set off a clostridial attack.

  • Clostridial diseases -- Sheep grazing outdoors can fall foul to any of the clostridial diseases if not correctly vaccinated. These diseases have been around for years, and we are all familiar with them in one form or another. The difficulty with them is when you do experience a clostridial attack, the losses can be enormous.


Bacteria multiply in damaged tissue or areas where there is no oxygen. Hence, the damaged liver caused by fluke is a real door-opener for these guys.

But they don't need fluke to let them in. They'll come in all on their own if the flock is not adequately protected. We will do a more detailed run-down on clostridia another day, but for this month of May, make sure your vaccine programme is in force.

  • Blow fly -- The flies are only starting and May is not as bad as later months, but we've already seen plenty of evidence of blow fly at farm level.

It's usually a ewe stricken with some other ailment that we're seeing with blow fly at this time of year. However, April has been mild and dry, and fly activity is earlier than other years. Keep the tails clean, clipped and clear of organic matter as required. As veterinary practitioners, it is a sickening sight to see a ewe presented for some particular ailment, only to find maggots eating raw flesh somewhere else on the body.

And so this month we pay attention to fluke, clostridia and blowfly. When covering fluke, we will also remember our other internal worms and parasites. Nematodirus is the most urgent one in need of attention in the young grazing lambs.

The early weeks of spring grazing will see a sudden surge of this parasite and so a good worming programme focuses on this guy from the start.

The other strongyle roundworms are typically seen later in the season, so dosing continues all year long.

The advice on good fluke dosing will also include the correct choice of medicine to keep the roundworms under control. Get that parasitic disease control programme written down and put in place this week. This is to prevent a large build-up of worms on the fresh pastures.

Peadar O Scanaill MVB MRCVS is a vet and member of Veterinary Ireland's Animal Health Committee. Email:

Indo Farming