EXPERIMENTAL POISONING OF CATTLE BY THE MUSHROOM RAMARIA-FLAVO-BRUNNESCENS (CLAVARIACEAE) - A STUDY OF THE MORPHOLOGY AND PATHOGENESIS OF LESIONS IN HOOVES, TAIL, HORNS AND TONGUE

Seven 2 to 7-mo-old calves were fed the mushroom Ramaria flavo-brunnes cens, Clinical signs of toxicosis included salivation, nasal serous di scharge, smoothing of the dorsum of the tongue, increased sensitivity in the hooves, reddening of the coronary bands, loss of the long hairs of the tip of the tail, softening of the base of the horns, and progr essive weight loss. Affected calves either died or were euthanatized i n extremis within 12-37 d from the initiation of feeding. Postmortem e xamination confirmed changes observed in the live calves. Histopatholo gic changes were marked in those structures where hard keratinization occurred and there normally is a high uptake of sulfur in the form of cystine during the keratinization process. Toxicosis appeared to alter the metabolism of sulfur-containing amino acids in keratinocytes, par ticularly cystine, with resultant strength loss in the molecular struc ture of hard keratin and loosening of the hooves, hairs and horns, and flattening of the lingual filiform papillae.