Diagnosis > Equine

Claviceps fungi although not endophytes, produce a similar array of ergot alkaloids. Ergot is the name given to the scelrotium of some species of Claviceps including Claviceps Purpurea and these may infect cereals and pasture grasses. Claviceps live on the plant without any benefit to the host, i.e. they are saprophytes. Claviceps cause the condition known as Ergotism which is historically the oldest known mycotoxicosis.  Claviceps live on a variety of pasture grasses and hay including ryegrass and bluegrass and commonly produce ergotamine, ergostine, ergocristine, ergocryptine and ergocornine. All the common cereals such as oats, barley and maize may be infected with ergot but rye seems more susceptible.

There have been clinical cases cited involving ergot alkaloids by Claviceps. In Brazil late gestation mares were fed oats containing ryegrass seed and suffered from foetal loss similar to those found with fescue toxicity. The ryegrass seed was the only source of ergot alkaloids. In another case pregnant mares were bedded on rye straw bedding and consumed the bedding. Of the first eight mares to foal, seven foaled dead foals. Investigation resulted in analysis of the bedding, which indicated the presence of two ergot alkaloids (one of which was ergocornine) at levels of 450ppb.

Intervention level
In the absence of information specifically for horses, the tolerance level of ergot in cereal grains in the USA is 0.3%. In the UK UKASTA standards are 0.001% ergot for feed cereal grains and zero tolerance for all other grains. It is thought that levels of 0.1% ergot in complete feeds for livestock will have an adverse effect.