From 1982 to 1989, inclusive, 20
poisonings were investigated by the Ontario Ministry of Agriculture and Food following ingestion by domestic livestock of granular
insecticides including
terbufos (13
poisonings),
disulfoton (two
poisonings),
fonofos (two
poisonings),
phorate (two
poisonings), and
carbofuran (one
poisoning); all are used for rootworm (Diabrotica spp.) control in corn. A further three
poisonings of livestock occurred following the ingestion of the foliar
insecticide,
endosulfan (two
poisonings), and the seed protectant
insecticides diazinon plus
lindane (one
poisoning). There were six
poisoning cases as a result of excessive topical applications of the three
insecticides coumpahos,
fenthion, and
lindane as dusts or sprays to control external parasites. Together, these events caused the deaths of 258 domestic animals of which 200 were cattle, 23 were swine, and 35 were sheep. Not all deaths are reported to the Ministry and the cases reported here may only represent 30-50% of the actual deaths over the period. Based on total populations of livestock, the percent losses were very small but they represent serious losses to individual growers. The economic loss is estimated at $160,000 over the eight years, or $20,000 per annum, and this does not include veterinary costs.Some of the poisoned animals died within as little as three to four hours of ingestion while others were sick but survived for several days. Lethal doses of
insecticide were found in the rumen, abomasum, or stomach of dead animals. Signs typical of
cholinesterase inhibition caused by
organophosphorus poisoning were observed in most cases.
Cholinesterase readings were found to be zero in dying animals. Necropsy findings were rarely more than
pulmonary edema or myocardial
hemorrhage. Where organochlorine
insecticides were ingested, convulsions were the major manifestation.Contamination of feed was most often accidental, and chemical analysis was most helpful in identifying both potent and minor sources, thus facilitating cleanup procedures.