The aim of the present study was to detect preliminarily the capacity and capability of a modified electrometric method for
use in the measurement of cholinesterase (ChE) activity in the blood of adult stray dogs. These values could be used for
comparison with the values of cholinesterase (ChE) activity in dogs exposed to organophosphorus and carbamate pesticides.
The highest activity of ChE (the change in pH / 30 minutes) in the blood plasma was 0.81, erythrocytes 0.73 and least in the
whole blood (0.67).There was no significant difference between EDTA and heparin when used as anticoagulants in blood
samples. To illustrate the accuracy of the way the coefficients of variation in blood plasma, erythrocytes and the whole blood
were 5.5%, 5.4% and 5%, respectively. This was done using 0.1 ml iodide acetylcholine iodide (7.5%). Quinidine sulfate
specifically inhibited pseudo ChE in the plasma, erythrocytes and whole blood, and it was estimated to be (4%, 28%, 6%),
whereas true ChE activity was (96%, 72%, 94%). Monocrotophos at a concentration (0.5, 1 μM) and carbaryl at (5, 10 μM)
significantly inhibited plasma, erythrocyte and whole blood ChE in vitro. These results suggest that the used modified
electrometric method is simple, precise, efficient and have the validity of measuring blood ChE activities in dogs.