With the recent wet and warm weather flies are out with vengeance once again; and with them comes the risk of fly strike. Fly strike is a severe skin infection caused by infestation with blowfly larvae.

The main risk factor for sheep is a soiled fleece which is common in ewes after turnout onto lush pasture. Lambs are often affected mid-summer onwards as parasitic enteritis becomes an issue.

The most effective prevention for ewes is full shearing, alternatively, dagging at turnout also works well. In lambs, tail docking and a good worm control programme are essential for reducing faecal soiling.

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In cattle, not only is fly worry a problem but transmission of summer mastitis is also a concern. Summer mastitis is usually a disease of non-lactating cows and heifers during the summer months. Typically caused by a group of different bacteria which act together to cause mastitis.

Transmission of infection is thought to be by the head fly (Hydrotea irritans). These flies live in bushes and trees and can only fly during mild, damp humid conditions and low wind speeds thus cases tend to be associated with "problem fields" next to woods and high hedges.

Affected quarters will become hot, hard, swollen and painful and may secrete a foul-smelling green/yellow discharge. The cow may isolate herself from the rest of the herd, become stiff and reluctant to walk, stop eating and rapidly lose body condition.

Veterinary treatment is essential and must be initiated quickly. The affected quarter is often lost and recovery from a severe case can take weeks. Prevention involves reducing the risk of exposure with good fly control and grazing management.

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Control of flies is almost impossible but using fly traps and the prompt removal of any fallen stock and wildlife carcasses may help to reduce numbers.

Products are available to both prevent and treat fly strike and fly worry. 

Ensure you are using the correct product for your livestock and situation.

For more information, to order fly products or to discuss cases on your farm, please phone the practice on 01751 469343 or contact info@derwentvalefarmvets.co.uk.

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