Determining Cholinesterase Reference Values in Birds

Around the world, compounds containing either organophosphates or carbamates are commonly used as agricultural pesticides. These compounds function well as anticholinesterases. The enzyme they target, cholinesterase, is found in most vertebrates in a few forms and helps the nervous system work properly by breaking down choline compounds, especially the neurotransmitter acetylcholine. Organophosphates and carbamates often affect many non-target species, including avian and mammalian wildlife. However, it is difficult to detect these compounds in the system due to, but not limited to, lack of crop and stomach contents and degradation of these compounds in the system. Due to this difficulty, cholinesterase levels are often used to determine whether a bird has been exposed to organophosphate and carbamate pesticides. In order to determine what an abnormal cholinesterase level is, a normal range is needed. This normal range is also referred to as a reference range. There are few established reference ranges for wildlife species. In order to determine reference values I looked at the results of past tests ran at the Wyoming State Veterinary Laboratory. After eliminating values from poisoned animals and outliers, I used SPSS to make histograms, determine standard deviation, median, and 95% confidence interval for multiple wildlife species. Using this information, I determined reference values. This information will help in the future when testing for anticholinesterase compound poisoning in wildlife.