Facial eczema is caused by a toxin produced by the spores of the fungus Pithomyces chartarum, which grows on pasture, especially in the base and in dead litter.
Facial eczema thrives in our area between December and May when our climate tends to be humid and warm. Prevention measures should be started during February if not earlier.
In these conditions, large numbers of spores build up which are eaten by grazing animals. Once eaten the spores release toxins, which damage the liver and bile ducts. The damaged liver can no longer detoxify waste products, and they build up. A breakdown product of chlorophyll builds up in the blood causing sensitivity to sunlight, which in turn causes inflammation of the skin with any UV exposure.
In severe cases, the skin can peel off, leaving large burn wounds that can become infected and cause severe pain and suffering. The un-pigmented white areas of the body are most susceptible to skin damage in cattle. In sheep, the face and ears are most susceptible to skin damage.
Animals with skin lesions only represent the tip of the iceberg as not all affected animals show obvious clinical signs. Up to 50% of the mob can have severe liver disease when only one or two of these animals are showing signs of skin damage.
Clinical signs may include:
- Shade seeking behaviour
- Rubbing, scratching, head shaking or restlessness
- The ears or face may be swollen
- Peeling, reddening or scabbing areas of the skin.
A badly damaged liver cannot regenerate, and since there is no cure for facial eczema, prevention is key. This needs to be in place well before the facial eczema season is due to start (ideally early January) and includes:
- Using preventative zinc supplements prior to the high-risk period is the MOST effective preventative method available. Face-Guard slow-release capsules that release zinc over a 6-8 week period are the best product available for lifestyle clients. If spore counts are high, a top up bolus may be required 6-8 weeks after the first. Sheep do not drink much water so treating water with zinc sulphate is not a reliable preventative option.
- Spore counts should be done on paddocks before grazing animals on them.
- Avoid paddocks with large amounts of shelter and dead litter at high risk periods, speed up rotation length, and supplementary feeding can also reduce spore intake.
Don’t forget to keep an eye on the Spore counts recorded on the web page, they have been collected from various farms throughout the district, but will always be several days old by the time they are published on Sundays. They are good for showing trends but you may get caught out if you wait for the results on the web site to be over 100,000.