Experts warning of late fluke danger later this winter a reminder for all Scottish sheep keepers

A new study involving 10 flocks in Argyll has highlighted the beneficial impact that the long, dry summer had in reducing the impact of liver fluke in sheep across the region.

However, veterinary experts involved in the study are urging sheep keepers to consider testing for fluke as there is a potential for heightened disease risk this winter. That is an important message for all sheep keepers in Scotland.

The Livestock Health Scotland project involves ten Argyll flocks which normally face significant liver fluke challenges and are in fluke hotspots. Set up with the support of SAC Campbeltown, the project is based on the Westwards and Dalriada veterinary groups with technical input and laboratory work carried out at the Moredun Research Institute by Philip Skuce and Gillian Mitchell.

The overall aim of the case studies is to track fluke activity in each flock through fluke egg counts from dung samples; testing the efficacy and potential for resistance to the key fluke control product triclabendazole and monitoring the impact of fluke control programs, designed by the farm vets.  A further aim is to consider alternatives to triclabendazole therapy, where resistance is suspected or confirmed.

Screening started in September with samples being taken at monthly or two weekly intervals. Across the flocks in both Kintyre and particularly in Mid-Argyll, there have been indications of chronic fluke infection but little evidence of a new fluke challenge; egg counts have remained near or at zero until late November when one flock showed a significant egg count and has been scheduled for triclabendazole efficacy testing.

Philip Skuce of Moredun said, ‘It has been very interesting to follow the liver fluke challenge in Argyll, a notorious hotspot for fluke, in what has proved to be an atypical year. It is all too easy to assume or guess the extent and timing of peak fluke challenge and what products may or may not be most effective. Our work in Argyll serves to reinforce the merits of regular monitoring and testing, as no two farms or years are the same!’

Livestock Health Scotland Chairman Nigel Miller, former President of NFU Scotland and a qualified vet added: “The sun and low rainfall in early summer appear to have broken the normal fluke challenge; however, a wet late summer and autumn may have given the parasite a lifeline and might trigger late infection in some flocks.

“The results so far are a good news story, evidence of an atypical year of sunshine. That said, with some producers routinely treating sheep for fluke in the autumn, to avoid clinical liver fluke disease, it is possible that doses were administered before infections were established. Late infections may break through in these flocks.  

“Screening will continue across the ten flocks and stronger indications of the level of late infection may emerge.  Those that have dosed early might discuss, with their own vet, the value of screening some ewes in January to ensure late infection is not building in their own flock.

Alison Barr of Dalriada Vets said "Devising annual fluke control strategies for our farm clients is challenging enough in years of "normal" rainfall. By December, in a typical year, many Argyll sheep would already have been dosed at least once for acute fluke. The results of the case studies so far have been very interesting. None of the five Mid Argyll farms have shown a strongly positive fluke infection-yet- suggesting that any Autumn/early Winter treatments administered up til now have possibly been too early.  Recent feedback from farms is that ewes are in fit condition, but we would urge flock masters to be vigilant and if in doubt about whether to dose or not to dose, speak to your vet and consider having samples analysed."

Donald Armour of Westwards Vets said: “This project has highlighted the difficulties in devising a one size fits all fluke control strategy. We have seen, over recent years, how unpredictable outbreaks of fluke can be on individual farms.

“The unique opportunity this project has offered us to map fluke burdens on different farms in similar localities has reinforced the benefit that all livestock farmers could gain through regular monitoring of parasite burdens on their farm.  

“It’s good to see that the good summer has resulted in a later than usual rise in fluke numbers, but no one should ever be complacent about the potential losses from disease caused by this parasite.”  

Notes to Editors

• The Livestock Health Scotland Argyll liver fluke studies have been supported by SAC, Kintyre Blackface Sheep Breeders, the Loiriston Trust, NFUS and Novartis Animal Health.

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Contact Bob Carruth on 0131 472 4006