Phosphoric acid ester preparations used in cattle, swine and sheep with special reference to cholinesterase activity. 3. Use of phosphoric acid ester preparations and their effect on acetylcholinesterase activity in swine]

The use of organophosphorus preparations in the treatment of ectoparasites and endoparasites of pigs is discussed. Treatment of 43 store pigs with preparations produced in the German Democratic Republic by washing and by the pour-on method resulted in considerable inactivation of acetylcholinesterase, which implies good systemic action. Overdosage increased this effect, but without producing signs of toxicity. The oral dosages for pigs cited in the literature were confirmed. Repeated treatment was recommended for the best results, as pigs rapidly break down the preparations. It is necessary to take into account adverse effects of oral administration on palatability of the ration and on weight gain. Addition of a preparation to a batch of food for a group of pigs is likely to be less successful than individual dosing, which is the best method for sows.