Laber, G. Investigation of pharmacokinetic parameters of tiamulin after intramuscular and subcutaneous administration in normal dogs.J. vet. Pharmacol. Therap.11, 45–49.Kinetic variables for tiamulin in the normal dog have been determined. Serum concentrations of tiamulin were compared after intramuscular (i.m.) and subcutaneous (s.c.) administration of a single dose of tiamulin. Following a single i.m. dose of 10 mg/kg body weight, the compound was calculated to have a Cmax= 0.61 ± 0.15 μg/ml, aTmax= 6 h and at½= 4.7 ± 1.4 h. Tiamulin showed dose‐dependent pharmacokinetics when given as a single s.c. dose of either 10 mg or 25 mg/kg body weight. For the lower dose, the values Cmax= 1.55 ± 0.11 μg/ml,Tmax= 8 h and1max= 4.28 ± 0.18 h were obtained. For the higher doseCmax= 3.14 ± 0.04 μg/ml,Tmax= 8 h andt½= 12.4 ± 3.4 h were calculated. When tiamulin was administered subcutaneously at a dose rate of 10 mg/kg body weight, higher and better maintained serum levels were achieved than those following i.m. administration. After repeated s.c. doses no significant accumulation of tiamulin occurred. Assuming that a continuous effective serum concentration is necessary throughout the course of therapy, these data would indicate that tiamulin should be gi