A very informative day with @farmersguardian and @virbac_uk as a panellist discussing Ovine Johnes Disease, an iceberg disease (slow to develop) affecting the sheep industry.
I'll hold my hands up and say I wasn't aware of OJD prior to this event, presuming it was only prevalent in cattle. It is referred to as the silent killer for a number of reasons, such as lack of awareness and the fact there are no clinical symptoms until later in life.
These include emaciation, poor fleece and low body condition score, but not scouring as seen in cattle, hence it is difficult to diagnose if showing no clinical signs. Testing can be done via blood or faecal samples, but at present only 5% of farmers test for OJD.
A bacterial disease spread via manure and milk, it can live in the soil for months. Young animals are most susceptible due to weaker immune systems, but the one-shot Gudair vaccine administered within the first six months of life has been shown to reduce mortality and bacteria shed by 90%.
It is recommended to vaccinate replacement ewe lambs before this age, and to buy in replacements from an OJD-free or vaccinated flock, to reduce the spread of the disease.
It is worrying how few farmers - me included - are aware of this and other iceberg diseases and the impacts they cause. Improved testing and proven vaccine results will hopefully increase awareness of the disease and increase productivity in the flock.
