Cholinesterase activity in plasma, red blood cells, muscle, and brain of dogs following repeated exposure to Spotton (fenthion)
Sundlof, S.F.; Clemmons, R.M.; Meyer, D.J.; Rappaport, J.J.; Fossler, M.E.; Hubbell, J.
Veterinary and Human Toxicology 26(2): 112-117
1984
ISSN/ISBN: 0145-6296 PMID: 6730296 Document Number: 236252
Over a three-year period several dogs seen with a variety of neurological abnormalities had a history of repeated and prolonged exposure to fenthion solution applied along the back for flea control. Fenthion is commonly used in dogs, although it is not officially approved for dogs and cats. Fifteen experimental adult mongrel dogs received, weekly, four applications of the solution at doses of 33 or 44 mg/kg body weight. Plasma cholinesterase values fell by about 80%, muscle cholinesterase by 55% and brain cholinesterase by 67%. RBC cholinesterase values were unaffected, and the absence of clinical signs was suggested to be due to fenthion-induced tolerance.