Serum Butyrylcholinesterase Activity in Healthy Dogs with and Without Exposure to Diazinon.

Background: Cholinesterase is a biomarker for poisonings by anticholinesterase agents, but its reference values are scarce, and possible interaction with collars containing parasiticides has not been studied.Objectives: We aimed to evaluate the serum cholinesterase activity of healthy dogs without a history of contact with anticholinesterase agents and healthy animals exposed to commercial collars containing organophosphate.Methods: Time 0 values were 4622.38 +/- 1311.53 U/L. After 7 days, a significant decay was observed, with a mean of 3934.45 +/- 1430.45 U/L. Spearman's test was performed, finding a weak correlation between ALT, creatinine, total plasma proteins, age, weight, red blood cells, platelets, leukocytes, and BuchE activities. In experiment 2, the mean at time 0 was 4753 +/- 454.8 U/L. With exposure to the collar, there was a decay of up to 93% after 14 days.Conclusions: Normality values of serum BuchE in healthy dogs without a history of exposure to anticholinesterase agents were 4360.8-4883.96 U/L. Freezing serum caused a decrease in BuchE activity. Exposure to commercial collars containing diazinon also reduced BuchE activity without clinical signs, indicating that previously exposed animals should be evaluated carefully.