Facial Eczema in Cattle

Facial eczema (Pithomycotoxicosis) on cattle causes a painful condition that resembles a sunburn. Pasture plants become infected with the fungus Pithomyces chartarum which produces a substance known as "sporidesmin." The spores adhere to the cattle's hair and skin. The toxic substance enters the cow's skin and makes its way towards the liver. Once there the substance causes widespread destruction to the liver and bile ducts. The damage that the liver sustains causes the skin eczema to manifest.

  1. Symptoms

    • The symptoms manifest themselves 20 days after exposure to the spores, according to the Department of Primary Industries State Government of Victoria. The skin of infected cows will show a lack of pigmentation, known as photodynamic dermatitis. The areas affected will be both the light and dark skin of the animal. Dairy cows often develop sores on their udders and teats which become extremely painful. Their milk production will become dramatically reduced.

    Progression

    • Depending on the amount of toxin ingested, the symptoms may progress to severe weight loss, lethargy and disinterest in food. Biliary obstruction is common, which causes the cow to show signs of jaundice, according to the Merck Veterinary Manual. Death is rare but can occur months after ingestion of the toxin due to widespread liver damage.

    Disease Development

    • The fungus requires warm, moist conditions to develop. Abundant humidity also aids in the development of the fungus. The fungus occurs widely in New Zealand from February to May. The fungus is invisible to the naked eye but grows in a cluster fashion that resembles mushrooms.

    Spore Production

    • The fungus has the capability of producing millions of toxic spores. The spores rapidly lose their toxicity over the course of one to two weeks. The fungus is widespread on perennial ryegrass. The fungus appears at the bottom of the blades of grass. Due to the prevalence of the fungus at ground level, low grass grazing should be discouraged in all cattle to limit the amount of toxins the animal may consume.

    Prevention

    • Always graze cattle on long grass to help prevent the consumption of the toxic spores. Avoid feeding cattle hay that has been cut late in the season since it may contain a high level of toxic spores. The spores flourish in areas of grass that have shelter from the wind so eliminating windbreaks might help reduce the abundance of toxic spores.

    Control

    • Spraying benzimidazole fungicide during the height of the season helps to reduce the spore production. Infected cattle must be kept out of direct sunlight and fed only on dry, clean pasture until the animal's system manages to overcome the toxins or it succumbs. Cattle administered zinc often suffer less from the toxin.