Farmers have a real opportunity to review their fluke control strategy this spring and there are three vital pieces of information that have come to light recently that they can consider when deciding on the best course of action:
1. A recent study published in the Veterinary Record looked at a flock of sheep diagnosed with fluke (Fasciola hepatica) and treated with triclabendazole.1 Resistance to triclabendazole was confirmed and the cost of additional treatments, ewe deaths and increased feed costs was estimated at £8.73 per ewe. The investigators concluded, ‘It is essential that farmers should attempt to reduce their reliance on metaphylactic triclabendazole treatments by developing evasive strategies, such as fencing off snail habitats; managing snail habitats and areas that are conducive to the survival of free-living stages of F. hepatica; and the strategic use of fasciolacidal anthelmintic treatments with the aim of reducing F. hepatica egg shedding and miracidal infection of snails.’
2. The year has got off to a warm start after the cold weather in December, with average daily temperatures already rising above 10 degrees centigrade – the temperature required for fluke development. This means some fluke development could have begun as early as March. In the Veterinary Record article, the researchers also make the point that changes in climate across the regions has made the risk period for metacercarial infection less predictable and they say many farmers have tried to overcome this by repeatedly using triclabendazole through late summer, autumn and winter. This strategy may, in fact, increase the likelihood of resistance.
3. According to NADIS, there are potentially large numbers of stock this spring that have been infected by last year’s moderate to high fluke population. NADIS also makes the point that, ‘The high efficacy of triclabendazole against early immature fluke is not generally needed at this time of year, and selection for resistance against this important drug can be reduced by saving it for use in the autumn.’2
So, the key considerations remain the need to rotate fluke treatments and to use treatments strategically. Spring treatments interrupt the fluke lifecyle and reduce pasture contamination, helping to ensure stock are in good condition through the spring when ewes are producing milk to feed lambs and into the summer months.
Treatment now should be focused on treating adult fluke to reduce egg laying and pasture infection. Closantel (Flukiver®) interrupts the fluke lifecycle for 13 weeks at this critical time by killing adult and immature fluke older than 5 – 6 weeks, while stunting younger immature fluke and reducing the hatchability of fluke eggs passed out in faeces.3 Flukiver has also been shown to be effective against fluke which are resistant to triclabendazole.4
References
- Sargison N. D., Scott P.R., Diagnosis and economic consequences of triclabendazole resistance in Fasciola hepatica in a sheep flock in south east Scotland, Veterinary Record (2011) 168, 159
- NADIS Parasite Forceast – May 2011
(http://www.nadis.org.uk/Current%20Bulletins/Parasite%20Forecast.pdf)
- Maes L, Vanparijs O, Lauwers H, Deckers W. Comparative efficacy of closantel and triclabendazole against Fasciola hepatica in experimentally infected sheep. Veterinary Record, Vol 127 No 18, 450-452 (1990)
- Coles G C, Rhodes A C, Stafford K A. Activity of closantel against triclabendazole resistant Fasciola hepatica. Veterinary Record, Vol 146, 504 (2000)
Flukiver® 5% w/v Oral Suspension contains 50 mg/ml closantel Legal category POM-VPS.
For further information contact Janssen Animal Health, 50-100 Holmers Farm Way, High Wycombe, Bucks, HP12 4EG Tel 01494 567555 Fax 01494 567556 Email: ahealth@its.jnj.com www.janssenanimalhealth.com/uk
Advice on the use of this or alternative medicines should be sought from the medicine prescriber
Use Animal Medicines Responsibly http://www.noah.co.uk/responsible/
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