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Each sclerotium (a compact collection of mycelia) of the fungus is a hard, black, elongated body
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It destroys and replaces a grain or seed of the maturing plant
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The sclerotia constitute the substance called ergot that has poisonous properties
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Ergot contains a variety of toxic substances
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These include derivatives of lysergic acid (ergotamine) and isolysergic acid (ergocristine)
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In past, humans got poisoned by contaminated flour
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In animals, including birds, poisoning may occur through the feeding of contaminated grain, but in herbivores, it results usually from the use of hay or straw containing a considerable proportion of parasitized plants
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In general, action of ergot is to stimulate smooth muscle by stimulating adrenergic nerves
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This action on the uterus is responsible for its use as an oxytocic
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Long-continued contraction of the vascular musculature is the main reason for its poisonous effects
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Clinical signs of chronic poisoning by ergot, known as “Ergotism” consist of dry gangrene of the limbs, tail and ears
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After weeks of ingestion of small amounts the most distal parts of the extremities may drop off
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The early stages are characterized by lameness, irregular gait and evidence of pain in the feet
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Palpation shows the parts to be cold and insensitive
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Sometimes, gangrene is moist instead of dry, at least in the feet
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A clear line of demarcation and an inflammatory zone just proximal to it usually exist
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In birds, comb, tongue and beak become gangrenous
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Less common signs based upon involvement of the gastrointestinal musculature include indigestion, colic, vomiting and either diarrhoea or constipation
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Pregnant animals usually abort
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Decrease milk production (agalactia) occurs
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This may be the only sign in pigs
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The signs described above characterize the usual “Gangrenous form”
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The rare “Spasmodic form” (convulsive form, nervous form) causes toxic contractions of the flexor muscles of the limb, trembling of the muscles, opisthotonus (an arched position of the body), tetanic spasms of the whole body, convulsions and death
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This type of reaction is believed to be due to failing blood supply in the central nervous system
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Lesions are seen in the gangrenous cases
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Also, congestion and sometimes haemorrhages are present in the visceral organs
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Gangrenous ergotism is identical in appearance to fescue poisoning.
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