Efficacy dose determination study of tilmicosin phosphate in feed for control of pneumonia caused by Actinobacillus pleuropneumoniae in swine

Abstract

Objective. To determine the effective dosage of tilmicosin phosphate when fed to pigs for the control of pneumonia attributable to Actinobacillus pleuropneumoniae. Design. Randomized complete block design, with initial weight as the blocking factor. Animals. Seeder pigs were used to infect clinically normal male and female pigs weighing between 13.6 and 36.3 kg at each of 4 trials. Procedure. Five doses of tilmicosin phosphate (0, 100, 200, 300, and 400 μg/g) were fed to pigs for 21 days. Pigs received experimental feeds 7 days before the seeder pigs were placed into pens. Feeding continued for an additional 14 days, with seeder pigs removed 3 to 8 days after placement. All pigs were euthanatized and necropsied, with lung bacterial flora and percentages of pneumonic involvement determined. Results. Improvenent in clinical impression score, daily rectal temperature, and weight gain were seen for all doses of tilmicosin, compared with controls. For the same variables, tilmicosin administered at 200 to 400 μg/g resulted in improvements over the 100 μg/g dose. Conclusions. Data indicate that tilmicosin phosphate fed to pigs at 200 to 400 μg/g is effective in controlling and preventing A pleuropneumoniae-induced pneumonia, when administered in feed for 21 days.