Intoxicação experimental por Manihot glaziovii Muel Arg. em caprinos na Paraíba.

Abstract

Cyanogenic plants had hydrocyanic acid as active principle, which is bound to cyanogenic glycosides, and liberated after the hydrolysis of these compounds. In Brazil the important toxic cyanogenic plants are: Manihot spp. (Euporbiaceae), including Manihot, esculenta (cassava) and many wild species of Manihot; Anadenanthera colubrina (sinonimus: Anadenanathera macrocarpa and Piptadenia macrocarpa) and Piptadenia viridiflora, trees from the Leguminoseae Mimosideae family; Sorghum spp. (gramineae); and Prunus sellowii and P. sphaerocarpa, trees from the Rosaceae family. The intoxication by M. esculenta occurs, frequently, when ruminants consume the roots shortly after collection. The intoxication by wild Manihot spp occurs when cattle or goats consume the plant after sprouting. The intoxication by Anadenanathera spp. and Prunus spp. occurs, when ruminants consume leaves from fallen trees or branches, and the intoxication by Sorghum spp. occurs after the ingestion of the sprouting young plants. Few outbreaks of intoxication by Cynodon dactylon (Tifton) had been reported. Because the fast absorption of cyanide, clinical signs of cyanide intoxication are observed immediately after or during plant ingestion. They are characterized by increased respiratory and cardiac frequencies, cyanotic mucous membranes, salivation, intense muscular tremors, nystagmus, incoordination, and falling, followed by lateral recumbence, opisthotonos, accentuated dispnea, paddling movements, and finally coma. Death occurs due to respiratory failure between 15 minutes and few hours after first clinical signs. If ingested in low doses, cyanide also can cause chronic intoxication, with lesions on the nervous system, thyroid and other organs. Cyanide is detoxicated by enzyme rodanase which change it to tiocyanate, which is a not toxic substance. Cyanide can be detoxicated by grunding or trituration, hay production, heating to remove the residues of free cyanide; by pressing, where the soluble cyanogenic glycosides are dragged with the water; by cooking; by fermentation; and by or dehydratation. Affected animals are treated by the intravenous administration of 50 ml for 100 kg body weight of a sodium tiosulfate 20% solution. The prevention of the intoxication is by avoiding the ingestion of large amounts of the toxic plants in a short period.