Determination of the Median Toxic Dose of Type C Botulinum Toxin in Lactating Dairy Cows

Abstract

Because of the difficulty in identifying botulinum toxin in cattle, it is hypothesized that cattle are sensitive to levels of toxin below the detection limits of current diagnostic techniques (the mouse protection bioassay and the immunostick enzyme-linked immunosorbent assay [ELISA] for type C botulinum toxin). Using an up-down method for toxicologic testing, the median toxic dose (MTD50) for cattle was determined. Four lactating Holstein cows were dosed at 0.125 or 0.25 ng/kg with Clostridium botulinum type C toxin and failed to develop clinical signs of botulism during the 7-day observation period. Three cows given 0.50 ng/kg of toxin developed clinical signs of botulism. From these results, the MTD50 was calculated at 0.388 ng/kg (3.88 mouse lethal doses/kg) using the trim-logit method. These results suggest that cattle are 12.88 times more sensitive to type C botulinum toxin than a mouse on a per kilogram weight basis. The mouse protection bioassay and the immunostick ELISA for type C botulinum toxin failed to identify the presence of the toxin in the serum, blood, and milk samples taken from all 7 animals.

Acute Type C Botulism with Fatal Consequences in a Holstein Breeding Establishment in Northern Italy

“…The neurological disorders identified through detailed examination of the animals were similar to those already discussed by other authors in cases of botulism in cattle [1][2][3]6,8,11,12]. Other toxigenic bacteria (e.g.…”

“…Botulism outbreaks caused by indirect or direct contamination of feed by poultry litter had already been presumed and described by several authors [8,13,15,16,26,27]. Other authors have described type C botulism in cattle that had been fed ensiled poultry litter as an additive, or cases where the animals had free access to poultry litter [28][29][30].…”

“…Cl. botulinum is classified into 7 or 8 different types (A, B, C (C 1 , C 2 ), D, E, F, G) depending on the antigen properties of the botulinum neurotoxins (BoNT) produced, with intoxication mostly appearing in cattle following the ingestion of neurotoxins of type C and D and, less frequently, of type B [5][6][7][8][9]. The clinical signs are caused by highly specific neurotoxins that inhibit the release of neurotransmitters by exocytosis, leading to paralysis [1,2,5].…”

Pré-compostagem de cadáveres de bovinos acometidos pelo botulismo

“…No entanto, diante desta situação o diagnóstico laboratorial negativo não exclui a possibilidade da intoxicação, prevalecendo o diagnóstico clínico-patológico e epidemiológico. Esta particularidade deve-se à sensibilidade do bioensaio em camundongo, que é de 43,1% quando se analisam amostras de fígado e conteúdos ruminal e intestinal de bovinos suspeitos (Dutra 2001) e ainda à alta suscetibilidade dos bovinos diante da toxina botulínica tipo C, quando comparados com os camundongos que são 12,88 vezes menos sensíveis (Moeller et al 2003) Por outro lado, a presença de esporos de C. botulinum tipo C nos conteúdos ruminal e intestinal foi confirmada somente em um dos cinco bovinos avaliados. Este aparente paradoxo entre os tipos de toxina envolvidos na intoxicação e a bacté-ria presente no trato gastrintestinal deve-se, provavelmente, às características do botulismo bovino, em que os dois tipos (C e D) são os responsáveis pela intoxicação, podendo inclusive ser encontrados normalmente na microbiota intestinal, ou ainda pelo pequeno número de amostras avaliadas.…”

Botulismo em bovinos leiteiros no Sul de Minas Gerais, Brasil

“…Embora vários autores tenham relatado a ausência de toxina botulínica no leite de bovinos acometidos pelo botulismo (GALEY et al, 2000;MOLLER et al, 2003), não existe um consenso a esse respeito e muitos autores indicam o descarte do leite dos lotes acometidos por até 14 dias após o último caso clínico (COBB et al, 2002). Essa medida de proteção ao consumidor aumenta ainda mais o ônus ocasionado pela doença em rebanhos leiteiros.…”