Breed Health


The Greyface Dartmoor sheep carries a fleece that is suitable to withstand the wet weather that it would have to endure on the slopes of Dartmoor.  One of the breed strengths was the fleece; such a heavy fleece of high value, would have contributed considerably to the rent due for the farm. Times change and wool is not valued.  However, the heavy fleece remains.  These sheep, as is the tradition in the UK are usually shorn once a year.  The Code of Recommendations for the Welfare of Livestock – sheep ( Livestock welfare-sheep )  states that every mature sheep should have its fleece removed at least once a year and that winter shearing is not a suitable practice unless the sheep are housed.  The DSBA Animal Welfare Policy (D.S.B.A. Welfare Policy) states that Greyface Dartmoor sheep must not be shorn before the 1st April and no later than the 31st July.

The recommendation is for all sheep to be shorn sometime between 1st April, at the very earliest and only if there is suitable protection from the weather, and the 31st July.  We would say, shear the sheep when they are fit to be sheared, so the warm weather would allow the grease to rise in the wool and it becomes ‘ripe’ for shearing.  Shearing a sheep that is not fit to be sheared is a difficult process for both the sheep and the shearer.

Shearing the Greyface Dartmoor sheep twice in a year is not normal practice and neither is it recommended.  If the sheep are shorn in April, then they will carry a very heavy fleece into the autumn and winter and problems will ensue.  If however, the sheep are shorn in May/June, then they carry less fleece during the autumn winter and a better balance of management can be attained.

Lambs must sheared in their year of birth. The Articles of Association state all sheep to be shorn by 31st July. Lambs must have been shorn if they are to be shown and/or inspected. For shows after 10th June, then sheep must have been shorn – including the lambs. Please read the show schedules and adhere to the rules or risk being disqualified.


SCOPS is an industry led group that represents the interests of the sheep industry. It recognises that, left unchecked, anthelmintic resistance (AR) is one of the biggest challenges to the future health and profitability of the UK sheep industry.

The SCOPS group was formed to develop sustainable strategies for parasite control in sheep, facilitate and oversee the delivery of these recommendations to the industry and ensure that new research and development is incorporated to refine and improve advice given to the sheep industry.

For further information please follow this link

Nadis – focussing on animal health skills

NADIS leaflet-1a

Using sheep wormers effectively

WHY DO WE NEED TO CHANGE? For many years we have enjoyed good worm control in our flocks but this has become increasingly reliant on anthelmintics (wormers) and unfortunately it has speeded up the development of anthelmintics resistance. Current control strategies are mostly based on a ‘blue-print’ with ewes and lambs being drenched to a set pattern during the year. This offers good control while the anthelmintics remain effective, but often results in overuse of products and a lack of targeting for specific parasites.

HOW DOES ANTHELMINTIC RESISTANCE DEVELOP? Every time we use anthelmintics, worms that are susceptible to its chemical activity are killed and, if present, any that are resistant survive. Over time, the continued use of that chemical will result in an increasing proportion of resistant worms and eventually this will be high enough so that wormy sheep do not respond to treatment. This process can be slowed or speeded up by certain management practices.

IS IT TOO LATE? No! For the majority of farms it is not too late to take action to slow the progress of anthelmintics resistance. Although we can find worms that are resistant to the BZ (white) wormers on the majority of farms, it may not have reached a level that causes an obvious problem on many of them. For the levamisole (yellow LM) drenches, resistance is still much less common and for macrocyclic-lactone (clear ML) wormers it is rare. If we act now, we can preserve the activity of the ML group in particular for a number of years.

NEW STRATEGIES – TAKING THE FIRST STEPS The new recommendations fall into 2 general categories:

1. Basic good practice – using anthelmintics properly and getting the best from each drench used

2. Reducing Selection Pressure – avoiding the over-use of anthelmintics and avoiding other practices which select rapidly for resistance.

This leaflet summarises the main things sheep farmers should now consider when planning their worm control. Some, highlighted in green are straightforward and relatively easy to implement. The others, in blue are more complex and will require time and discussion with your vet or adviser.


Not all farms have resistant worms so quarantine treatments are vital to ensure that any in-coming sheep don’t bring resistance with them. Follow these 3 steps:

i) – Drench ALL in-coming sheep with a levamisole (yellow) drench and give them an ML (clear drench or injectable). The use of two products minimises the risk of any resistant worms surviving.

ii) – Keep them off pasture for 24-48 hours so that all the worm eggs have been passed.

iii) -Turn them out on to dirty pasture to make sure any eggs form worms that may have survived treatment are diluted by worm eggs already on the pasture.


Always dose to the heaviest in the group – don’t guess, weigh them! Then check that the dosing gun is working properly by discharging it several times into a syringe or measuring jug. Make sure that the drench goes over the back of the tongue and where possible restrict access to feed before administering BZ (white) or ML (clear) drenches (but never for pregnant ewes).


Find out which drenches are working effectively on your farm by taking faeces samples before and some days after drenching. Ask your Vet. for details of how this simple test can be done. Then plan a strategy that takes account of your current resistance status with the aim of maintaining the effectiveness of the chemical groups that are still working.


Are you drenching to a set pattern every year? If so, it’s time to sit down and look at the reasoning behind each treatment and whether there is scope to reduce the number of treatments or to target them better. Consult your vet or adviser and look at how you can implement these recommendations. Some strategies can be put into practice quickly, while others will take time – but the sooner you act the longer the drenches will work for you.


Looking for ways to use grazing management to reduce worm burdens remains an important part of worm control. Pasture such as aftermath or even areas that have just carried dry adult sheep will have lower worm burdens. Lambs on these pastures will require fewer treatments. CAP Reform may even give us more opportunities for this in the future as stocking rates fall and new systems evolve.

The advances being made with rams selected for resistance to worms will also offer the option to reduce anthelmintics use in the future.


Faecal Egg Count (FEC) monitoring has an important part to play in determining when and which sheep to drench. Sheep farmers who regularly use FECs use less drench overall and therefore reduce the selection pressure for resistant worms. Minimising the treatments given to mature sheep that are immune to most worm species is also important. If adult sheep are fit and healthy the need to treat them is limited and some practices, for example blanket pre-tupping treatments, should be questioned.


Monitoring can also be used to show which parasites are present and this helps to reduce the use of broad spectrum anthelmintics. For example, liver fluke can be treated with flukicide products that do not contain any of the wormer groups. The Barber’s Pole worm (Haemonchus contortus) can also be treated with a narrow spectrum wormer. This can significantly reduce the unnecessary use of the anthelmintics we need to preserve, particularly in adult sheep. It is also often cheaper!


This is the hardest recommendation to implement. However, we must begin to think about preserving susceptible worms on farms in the future. There are two main things to consider:

i) Mature sheep are immune to most worm species, so the need to treat them is limited. An exception is ewes for a few weeks around lambing. Even if treatment is necessary for some sheep, leaving just a few of them untreated you will help to preserve some susceptible worms on your farm.

ii) Turning newly drenched sheep on to clean pasture means that the pasture will only be populated by resistant worms. This is highly selective for resistance. But clean pastures are good for the sheep, so how do we get around this? There are two possible compromises:

Treat them a few days before moving OR leave a small number of sheep untreated.