PESQUISA VETERINÁRIA BRASILEIRA

Abstract in English:

ABSTRACT.- Helayel M.A., Caldas S.A., Peixoto T.C., França, T.N., Tokarnia C.H., Döbereiner J., Nogueira V.A. & Peixoto P.V. 2011. [Antagonism of acetamid in experiments with sheep, goats and rabbits indicates that monofluoroacetate is the toxic principle of Pseudocalymma elegans Bignoniaceae.] O antagonismo com acetamida em experimentos com ovinos, caprinos e coelhos indica monofluoroacetato como princípio tóxico de Pseudocalymma elegans Bignoniaceae. Pesquisa Veterinária Brasileira 31(10):867-874. Projeto Sanidade Animal Embrapa/UFRRJ, Seropédica, RJ 23890-000, Brazil. E-mail: michel_abdallavet@yahoo.com.br This study aimed to evaluate the protective effect of acetamid in experimental poisoning by Pseudocalymma elegans in sheep, goats and rabbits, in order to prove indirectly that monofluoroacetate (MF) is responsible for the clinical signs and death of animals that ingested the plant. Experiments were performed to determine for sheep and goats the lethal dose of P. elegans collected in Rio Bonito, RJ, in different seasons, and to adjust the dose of acetamid to be administered. - In the first experiment, two sheep and two goats received 1.0g/kg of fresh P. elegans, and two (one sheep and one goat) were pretreated with 2.0g/kg of acetamid. None of the animals showed clinical signs or died. Possibly, the plant could be less toxic, since it was collected at the end of the rainy season. - In the second experiment, two sheep and two goats received 0.67 and 1.0g/kg of the dried plant, after pretreatment with 2.0 and 3.0g/kg of acetamid, respectively. All animals died, as the administered doses of P. elegans were very high. - In the third experiment, two sheep and two goats received 0.333g/kg of dried P. elegans after previous administration of 2.0g/kg of acetamid; a week later, the protocol above was repeated, but without the antidote. In experiments with rabbits, doses of 0.5 and 1.0g/kg of dried P. elegans were given after administration of 3.0g/kg of acetamid; seven days later, the same protocol was repeated, except the administration of acetamide. This procedure, when acetamid was administered before, prevented the appearance of clinical signs and death of sheep, goats and rabbits. But the animals not treated with acetamid showed symptoms of poisoning and died. Clinically, the sheep and goats had tachycardia, engorged jugular vein, positive venous pulse, lateral recumbence, and muscle tremors. In the “dramatic phase”, the animals fell into lateral position, stretched the limbs, were paddling and died within minutes. The rabbits showed apathy, muscle tremors, vocalization and lateral decumbence minutes before death. At postmortem examination, the sheep and goats had engorged jugular veins and atria, dilated vena cava cranialis and caudalis, as well as pulmonary edema, hepatic congestion and edema of the gallbladder subserosa. In rabbits, the main macroscopic alterations were dilated atria, engorged vena cava cranialis and caudalis, and congested liver and diaphragm vessels. Histopathology revealed, in two sheep and one goat, vacuolar-hydropic degeneration of the distal convoluted kidney tubules, together with caryopicnosis. In the rabbits, the liver showed severe congestion with numerous shock corpuscles. The experimental results show indirectly that MF is to be held responsible for death of the animals that ingested P. elegans; since “acetate donor” compounds, such as acetamid, are capable to reduce the competitive inhibition of MF for the same active site (Coenzyme A) which prevents the formation of fluorocitrate, its active metabolite, formed in the body through the so-called “lethal synthesis”.

• Pseudocalymma elegans acetamide poisonous plants acetamida plantas tóxicas

Abstract in Portuguese:

RESUMO.- Helayel M.A., Caldas S.A., Peixoto T.C., França, T.N., Tokarnia C.H., Döbereiner J., Nogueira V.A. & Peixoto P.V. 2011. [Antagonism of acetamid in experiments with sheep, goats and rabbits indicates that monofluoroacetate is the toxic principle of Pseudocalymma elegans Bignoniaceae.] O antagonismo com acetamida em experimentos com ovinos, caprinos e coelhos indica monofluoroacetato como princípio tóxico de Pseudocalymma elegans Bignoniaceae. Pesquisa Veterinária Brasileira 31(10):867-874. Projeto Sanidade Animal Embrapa/UFRRJ, Seropédica, RJ 23890-000, Brazil. E-mail: michel_abdallavet@yahoo.com.br

Abstract in English:

ABSTRACT.- Helayel M.A., França T.N., Seixas J.N., Nogueira V.A., Caldas S.A. & Peixoto P.V. 2009. [Sudden death in cattle caused by ingestion of Pseudocalymma elegans (Bignoniaceae) in the county of Rio Bonito, Rio de Janeiro.] Morte súbita em bovinos causada pela ingestão de Pseudocalymma elegans (Bignoniaceae) no município de Rio Bonito, RJ. Pesquisa Veterinária Brasileira 29(7):498-508. Curso de Pós-Graduação em Medicina Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: michel_abdallavet@yahoo.com.br Natural poisoning by Pseudocalymma elegans, a plant that causes “sudden death” and only occurs in the State of Rio de Janeiro, is described in a cow. This condition was experimentally reproduced in three calves and three rabbits with the plant collected in the area where the deaths had occurred. Postmortem and histopathological examinations of the natural case in the cow did not reveal significant alterations. Oral administration of 1g/kg of the sprouts of P. elegans caused death of the calf 5 hours and 30 minutes after beginning of the administration. The dose of 0.5 g/kg caused death of another calf with onset of symptoms after 3 hours and 24 minutes and a course of 73 hours and 12 minutes. Animals that ingest borderline doses may show a longer course with a characteristic clinical picture of heart impairment. The dose of 0.25g/kg did not cause death, but only clinical signs. Heart palpitation and arrhythmia, increase of breathing frequency, reluctance in moving, positive venous pulse, ingurgitated jugular veins, falling down and peddling movements shortly before death, were observed. At postmortem examination the lesions were those of acute heart insufficiency, and histopathological examination revealed the typical kidney lesion (hydropic-vacular degeneration in the distal convoluted tubules) seen in poisoning by plants that cause “sudden death”. In the experimentally poisoned rabbits the clinical course was less than 1-2 minutes. In the kidney of two rabbits there was also the characteristic microscopic lesion. The presence of the plant in the county of Rio Bonito had not been known by the veterinarians. It is concluded that the plant could be more toxic than described before.

• Poisonous plants Pseudocalymma elegans Bignoniaceae plant poisoning sudden death cattle rabbits

Abstract in Portuguese:

RESUMO.- Helayel M.A., França T.N., Seixas J.N., Nogueira V.A., Caldas S.A. & Peixoto P.V. 2009. [Sudden death in cattle caused by ingestion of Pseudocalymma elegans (Bignoniaceae) in the county of Rio Bonito, Rio de Janeiro.] Morte súbita em bovinos causada pela ingestão de Pseudocalymma elegans (Bignoniaceae) no município de Rio Bonito, RJ. Pesquisa Veterinária Brasileira 29(7):498-508. Curso de Pós-Graduação em Medicina Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23890-000, Brazil. E-mail: michel_abdallavet@yahoo.com.br Descreve-se a intoxicação natural por Pseudocalymma elegans em pelo menos um bovino em Rio Bonito, RJ e a reprodução experimental dessa intoxicação em três bovinos e em 3 coelhos com exemplares dessa planta colhida no local onde ocorreu a morte. Necropsia e histopatologia do bovino naturalmente intoxicado não revelaram alterações significativas. A administração, por via oral, de 1g/kg da brotação da planta causou a morte do bovino dentro de 5h e 30 minutos após o início da administração, já pela administração de 0,5 g/kg, a morte do animal ocorreu após 76 horas e 36 minutos. A dose de 0,25g/kg foi capaz de causar sintomas, mas não levou a morte. A sintomatologia caracterizou-se por arritmia cardíaca, taquicardia, aumento da freqüência respiratória, relutância em se mover, pulso venoso positivo, jugulares e grandes vasos ingurgitados, queda ao solo e movimentos de pedalagem, seguindo-se o óbito. À necropsia foram verificadas alterações compatíveis com às observadas na insuficiência cardíaca aguda, e o exame histopatológico revelou a lesão renal típica (degeneração hidrópica em túbulos contornados distais) de intoxicação por plantas que causam “morte súbita”. Nos coelhos, a evolução variou entre menos de um minuto a dois minutos. O exame histopatológico do rim de dois coelhos também revelou a lesão microscópica característica. Essa planta ainda não havia sido mapeada nessa área do Estado do Rio de Janeiro. Conclui-se que a planta pode ser mais tóxica do que anteriormente descrito.