What to look for
- A sudden drop in milk production
- Photosensitisation occurs about 10 days later when the skin becomes irritated
- Cows will be restless and seek shade, lick affected areas and rub skin raw against hard surfaces
- Weight loss due to liver damage
- May develop diarrhoea
Cause - a liver toxin from pasture fungus (Pithomyces chartarum)
Animals ingest the toxin (sporidesmin) produced by a fungus that grows on moist, dead grass. This fungus is relatively widespread in dairy areas in Victoria but only grows under very specific conditions. Facial eczema only occurs when the climatic conditions are suitable for rapid proliferation and production of large numbers of toxic spores.
Animals likely to be affected
Lactating dairy cows. It is usually seen in autumn with small outbreaks occurring in Gippsland and, less frequently in other districts.
Other diseases with similar signs
Liver damage and photosensitisation caused by toxins from other plants such as perennial ryegrass, brassica crops and St John's Wort.
Confirming the diagnosis
Usually based on the clinical signs and high toxic spore counts in pasture. Blood tests can be used to confirm liver damage, and if an animal dies, post mortem examination of the liver will show characteristic changes.
Once the animal has liver damage there is no specific treatment, but the severity of the disease can be reduced by keeping animals in shade during the day and supporting them with anti-inflammatories, pain relief, good nursing, food and water. Most affected animals will recover but are likely to have reduced milk production. In some cases, the liver damage will be too severe for full recovery and these animals will be vulnerable to future outbreaks.
- Climatic conditions when the toxic fungus is likely to multiply to dangerous levels - a succession of moist warm evenings in autumn
- Animals grazing pasture containing a substantial amount of dead material
- Previous exposure to toxins that cause liver damage
Pasture spore monitoring is indicated when conditions are favourable for fungal production of sporedesmin. If pasture spore counts identify dangerous conditions, keep animals off pastures that contain high levels of moist dead pasture and consider feeding zinc supplements to protect animals from toxicity.
Preventing facial eczema in milking cows using zinc oxide in feed (PDF, 231KB)
Zinc supplements can be effective for facial eczema control and prevention if well managed. This resource includes a checklist for zinc oxide supplementation in feed.