Dealing with health challenges on sheep farms

Poor weather not only created grassland management difficulties on sheep farms, it has resulted in a higher than usual number of problem cases in both ewes and lambs. Here, the Teagasc Sheep Specialist team look at the main health challenges, while outlining strategies to overcome them.

Grass tetany

Challenging weather and difficult grazing conditions means grass tetany still poses a risk.

• Keep preventative measures in place.
• Use a number of high magnesium buckets/blocks in different locations around the grazing area to encourage intake.
• Keep buckets/blocks free of soil/faecal matter.
• Do not use blocks designed for dairy/suckler cows, as they will contain levels of copper which are toxic to sheep.

Parasite challenge

Coccidiosis

Coccidiosis is a parasite that primarily effects lambs from two weeks up to 8-9 weeks of age. Affected lambs present with diarrhoea, often containing mucus or blood. They may also show signs of straining and appear empty/dehydrated. Prompt treatment is needed by administering a suitable coccidiostat.

There are two main types of coccidastat. Diclazuril-based products interrupts the life cycle of the coccidia for two weeks. Consequently, when using this product, a repeat treatment may be needed 2-3 weeks after the initial treatment. These products have a short withdrawal period.

Toltrazuril-based products are active against all development stages of coccidia. It lasts longer in the lamb’s system, consequently one treatment is usually sufficient. However, these products tend to have a longer withdrawal period.

Additionally, to reduce the contamination/challenge, keep troughs/feeders free from faecal material and moved regularly.

Nematodirus

Nematodirus (battus) is the other main early season parasite which is pathogenic to young lambs. In general, it affects lambs aged from 6 to 12 weeks, but may occur in younger lambs that are grazing earlier, e.g. twins on ewes with poor milk yield.

• The maximum peak Nematodirus egg hatching has occurred from the end of March to the early days of April.
• Treat with Benzimidazole (1-BZ – white drench) based product.
• No product offers residual activity against Nematodirus, so a second treatment may be necessary - particularly in cases of mixed age grazing groups.

For more on the control of Nematodirus, listen in to a recent episode of the OviCast podcast, which featured Dr James O’Shaughnessy from the Department of Agriculture’s Central Veterinary Research Laboratory in Backweston:

Mastitis

Mastitis occurs as a result of bacterial infection of the udder. This year’s difficult weather, challenging grazing conditions, and over-suckling from lambs are all likely to have increased the risk. Mastitis will present in either clinical or subclinical form.

Clinical

Per acute mastitis is where ewes will present with swollen, discoloured mammary as a result of gangrene setting in (blue bag). Even with prompt treatment, this will often be fatal due to the toxins involved.

Acute mastitis presents as a swollen mammary, filled with watery fluid or pus-like secretions. When early treatment is administered, prognosis is better than acute mastitis. These ewes should be segregated, as often their lambs (hungry) will spread infection through cross suckling.

Key tips:

• Check regularly and observe for signs of ill health, lameness/discomfort and/or hungry lambs.
• Early intervention and treatment is necessary.
• Consult your vet for the most suitable antibiotic treatment, including anti-inflammatory and/or pain relief.
• Manage separately from the main flock and supplement and/or remove lambs where necessary.

Sub-clinical mastitis

This type of mastitis is what is often detected as lumps in the mammary. These ewes should considered strongly for culling, as they often present as acute cases in the following seasons.

Lameness

The most common cause of lameness in lambs at this stage is scald, identifiable as an irritated area between the digits of the hoof. As it will spread rapidly, early intervention is key.

In smaller flocks, individual treatment with topical sprays will be possible. In general, though, a whole flock approach is best. Footbathing of the flock in a 10% (1kg per 10L) zinc or copper sulphate solution, if done correctly, gives an excellent response in the treatment and prevention of scald.