title: 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.
authors.affiliation: California Animal Health and Food Safety Laboratory System, Tulare Laboratory, University of California, 18830 Road 112, Tulare, CA 93274, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Moeller
authors.forename: Birgit
authors.initials: B
authors.lastname: Puschner
authors.forename: Richard L
authors.initials: RL
authors.lastname: Walker
authors.forename: Tonie
authors.initials: T
authors.lastname: Rocke
authors.forename: Frank D
authors.initials: FD
authors.lastname: Galey
authors.forename: James S
authors.initials: JS
authors.lastname: Cullor
authors.forename: Alex A
authors.initials: AA
authors.lastname: Ardans
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000633:toxicity*; D002417:Cattle; D003014:Clostridium botulinum / Q000472:pathogenicity*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007774:Lactation; D007928:Lethal Dose 50; D011064:Poly Adenosine Diphosphate Ribose
chemical_list: D011064:Poly Adenosine Diphosphate Ribose; D001905:Botulinum Toxins; C096324:botulinum toxin type C