The panel (left to right) Bizza Walters, Ioan Humphreys, Fiona Lovatt, Ben Briggs,; Peers Davies, Maddy Lewis Ben Strugne
Ovine Johne’s Disease Is The First Disease Sheep Producers Should Be Tackling
8 months ago 
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Ovine Johne’s disease (OJD) is one of the UK’s biggest, but least known, threats to flock health. It is thought that some 70 per cent of UK flocks harbour the disease; a study in the UK in 2019 showed that 64% of sheep flocks tested, were positive for Johne’s. 1 To explore the implications of this ‘iceberg disease’ in sheep, Virbac recently partnered with Farmers Guardian to assemble leading authorities and independent sheep farmers for an in depth round table discussion on the negative and costly effects of Johnes disease.
The panel:
- Bizza Walters, [mixed family farm in Warwickshire lambing 600 North Country Mules to Suffolk tups]
- Ioan Humphreys, [sheep, beef and poultry farmer in Powys, lambing 850 ewes]
- Fiona Lovatt, [specialist independent vet in sheep health and production and a clinical associate professor at the University of Nottingham]
- Ben Briggs, - session chair [Agriconnect group publisher]
- Dr Peers Davies, [vet and researcher at the University of Liverpool, specialist in Johne’s disease]
- Maddy Lewis, [sheep farmer near Aberystwyth, lambing 300 ewes and selling rams through Innovis]
- Ben Strugnell, [independent vet running carcass-based diagnostic service Farm Post Mortems].
The round table identified a worrying lack of awareness of Johne’s disease in sheep, with flockmasters shocked to discover its existence and the extent of the problem, a situation that highlighted the need for vets and farmers to collaborate to tackle this common chronic wasting disease caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP), which causes inflammation of the gut so animals are unable to absorb nutrients.
Dr Davies explained some of the ramifications of Johnes disease if left undetected. “Ewes will be metabolically inefficient, and this makes them less likely to get in-lamb. They will probably be culled as barreners before they have lost enough weight to become an obvious case. People will not be realising why ewes are not getting in-lamb; they will be attributing it to worms or fluke’. Bizza Walters agreed, saying that a thin ewe would most likely be attributed to worms rather than Jonhe’s disease being considered, and that her flock has never been tested. ‘If thinness is a major reason for culling in your flock, it is a sign OJD should be investigated’, said post-mortem specialist Ben Strugnell.
For every animal showing clinical symptoms of Johne’s disease, a further 10-15 will be shedding the bacterium but not showing any visible symptoms. Within a flock, infection rates can range from 2-3 per cent of animals affected, up to 75 per cent. An infected flock will typically have a replacement rate of about 30 per cent, compared with 22-24 per cent for an uninfected unit. “That is a huge additional cost, so understanding the economic importance of OJD in a flock is essential, and something vets could be helping clients with’, said Dr Davies.
Powys sheep, beef and poultry producer, Ioan Humphreys, said: “I knew about Johne’s in cattle, but had no idea about sheep and, looking back, I had a ewe a couple of months ago which had classic signs of it. We have a closed flock, health plans and regular meetings with our vet, but this has never been mentioned.” Ms Lewis, added, “If we have ewes with OJD who are piling out worm eggs all year round [because their immunity is compromised], it is another reason to vaccinate’.
Sheep vet Fiona Lovatt asserted that testing was key: “If you do not look, you will not find it, and people often just get rid of thin ewes. While vets might offer the cheaper option of blood testing, by far the most reliable result would be from sending in some pooled faecal samples from ewes suspected of having might have OJD and to perform a pooled PCR test’ she added.
Once a flock is infected with Johne’s eradication is almost impossible, so the aim is to control the disease by reducing the build-up of bacteria on the pasture therefore transmission. Although there is no licensed vaccine for Johne’s in cattle, there is a licensed vaccine for Johne’s in sheep.
Gudair®, is a one-shot lifetime vaccine and whilst vaccination won’t eliminate the bacteria nor remove all an infected flock’s problems overnight, it has been shown to be a very effective way of controlling Johne’s and significantly reducing the impact of the disease in infected flocks2.
‘The round table demonstrated the need for vets to consider Johnes in any unthrifty stock and include this in discussions when working with farmers to protect flock health, this is now of increased importance as the AHWP has set the control of iceberg diseases in sheep as a priority. Ultimately, controlling OJD within a flock will increase productivity in the long term.’ said Sabrina Jordan, Farm Product Manager Virbac UK ‘The benefits being; potentially fewer barreners; increasing productive life of the ewe for an additional 1-2 years and increased bodyweight at slaughter. In addition to this, there can be cross-over of Johne’s from sheep to cattle, so by controlling OJD in flocks, potentially you can help protect herds on mixed farms.’
Mr Strugnell, OJD is the number one disease he believes sheep producers should be tackling. He said: “For me, it is OJD first and all the others second, for two reasons. One, it is highly prevalent, and two, you can actually do something about it.”
For more information about Johne’s Disease in sheep, head over to NADIS https://www.nadis.org.uk/disease-a-z/sheep/johnes-disease-paratuberculosis/ or find out more from experts and sheep farmers’ experience of OJD at Farmers Guardian https://www.farmersguardian.com/sponsored-hub/virbac-sheep
References
- AHDB (2019) Iceberg diseases of ewes - Technical manual for vets, consultants and farmers
- Reddacliff L, Eppleston J, Windsor P, Whittington R, Jones S (2006) Efficacy of a killed vaccine for the control of paratuberculosis in Australian sheep flocks. Vet Microbiol. 115(1-3):77-90.
GUDAIR emulsion for injection for sheep and goats [POM-V]. For advice on the use of this or alternative medicines speak to your veterinary surgeon. Further information is available on the SPC or from from: Virbac Ltd. Woolpit Business Park, Windmill Avenue, Woolpit, Bury St. Edmunds, Suffolk IP30 9UP. Tel: +44 (0) 1359 243243 UK: Email [email protected]:
Use medicines responsibly www.noah.co.uk/responsible.
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