Facial eczema occurs when cattle ingest spores of the fungus Pithomyces chartarum. The spores contain a toxin, called sporidesmin, which damages the liver and bile ducts. One of the first signs of facial eczema may be a sudden drop in milk production and a short period of diarrhoea. However, often the most recognisable sign of facial eczema is inflammation of unpigmented skin and sensitivity to sunlight. This is called photosensitisation. This occurs because the damaged liver is unable to process breakdown products from the chlorophyll in grass and they build up in the bloodstream.
Not all animals affected with facial eczema will show symptoms when liver damage has occurred. Research conducted in New Zealand suggests that for every one clinical case of facial eczema, there may be a further 10 cows with liver damage and reduced milk production.
The treatment for facial eczema is non-specific and is aimed at reducing pain and irritation associated with photosensitisation. There is no cure for facial eczema.
The fungus Pithomyces chartarum grows in the dead leaf material at the base of pastures in warm, moist conditions in late summer and early autumn. Monitoring pasture spore counts can assist with identifying periods of pasture toxicity and when to implement preventative strategies.
Feeding zinc is protective for facial eczema. To be effective, the cow's blood serum zinc levels need to be maintained in the range of 20-35µmol/L. This is most reliably achieved by feeding zinc oxide in pre-formulated pellets at the correct dose rate. Controlled release, intra-ruminal zinc boluses used in New Zealand are not yet available in Australia. Importantly, feeding zinc will not reverse existing liver damage.
Spore monitoring program
Dairy Australia funds a spore monitoring program on approximately 30 sentinel farms across Gippsland and the Bega Valley from January to May each year. When local pasture spore counts are trending upwards to 20,000 spores/gram and weather conditions look favourable for spore formulation, each farm should begin monitoring their own pasture spore counts week to week or implement facial eczema prevention strategies.
The facial eczema spore monitoring program page has current spore counts and allows the user to subscribe to regular e-mail updates. If spore counts rise to dangerous levels, Dairy Australia will issue an alert via e-mail and SMS to all subscribers to begin monitoring their own pasture spore counts and/or commence feeding zinc oxide. Pasture spore testing services are currently offered by the following veterinary practices:
- West Gippsland Veterinary Centre (Warragul)
- Gippsland Veterinary Group (Leongatha)
- Yarram Veterinary Centre
- Maffra Veterinary Centre
- Bega and Cobargo Veterinary Clinic
- Snowy River Veterinary Clinic (Orbost)
Other classes of livestock (e.g. bulls, heifers, calves, dry stock) are also at risk of facial eczema and access to high spore count pastures may need to be restricted. If zinc oxide supplementation is not possible, consider:
- Not allowing these animals to graze pasture to a short length, even if it means leaving long residuals
- Supplementing stock with hay or silage to reduce pasture intake
- In more extreme situations, twice weekly drenching with zinc oxide is an option.
To learn more about facial eczema, watch the Preventing facial eczema outbreaks webinar.
Veterinarians and advisors can learn more about facial eczema by reading A Review of Facial Eczema (Pithomycotoxicosis) - Report of the Dairy Australia Facial Eczema Working Group (updated 2013).
More details about zinc supplementation for facial eczema prevention are outlined in Preventing facial eczema in milking cows using zinc oxide in feed.
A Review of Facial Eczema Pithomycotoxicosis(23 September 2020)PDF, 2.22 MB
Preventing facial eczema in milking cows using zinc oxide in feed(09 July 2020)PDF, 231.41 KB