Effects of sodium pentobarbital on insect growth rate and cattle decomposition

In the United States, sodium pentobarbital is the only chemical form of legal and humane euthanasia for animals.  However, the drug can contaminate the environment.  We studied effects of a lethal dose of 'Beauthansia-D Special' (Nembutal) on decomposition of calves, Bos taurus L., and developmental rates of necrophagous insects including bottle flies (family Calliphoridae), flesh flies (family Sarcophagidae), scavenger flies (family Sepsidae), rove beetles (family Staphylinidae), and scarab beetles (family Scarabaeidae) collected from the calves.  Rate of decomposition of the carcasses differed between the treatments, but there were no definable differences in rates of colonization by insect species.  Maggots in controlled experiments in an incubator developed significantly slower from the third instar to pupation when fed calf liver treated with sodium pentobarbital, at least a 24-hour delay before pupation.  There also was a significant delay in the number of days before adults emerged when maggots were fed liver treated with sodium pentobarbital.  Flies fed liver treated with sodium pentobarbital emerged 2-3 days later (14-15 days total) than flies fed liver that had not been treated.  Because of cold and erratic weather in 2013, decompositional stages of the carcasses were longer than in comparable studies, and comparison of successional data by treatment was inconclusive.