Retina, brain and blood cholinesterase levels in cats treated with oral dichlorvos.

Dichlorvos (DDVP) is used as an antihelmetic, principally in dogs, cats, pigs and horses. Retina, whole blood, erythrocyte, plasma and brain cholinesterase (ChE) activities were monitored following DDVP exposure in cats to establish their use as indicators of exposure to a ChE inhibitor. Following DDVP exposure, whole blood ChE activity was 16.8% of preexposure, erythrocyte ChE activity was 33% of preexposure, and plasma ChE was 19% of preexposure values. Brain and retinal ChE activities were reduced to 45% and 43% of control values. Retinal ChE paralleled brain activity.