The study aimed to define the effects of M. haemolytica and a single oral dose of albendazole on the single-dose pharmacokinetics of marbofloxacin in lambs. The pharmacokinetic–pharmacodynamic integration of marbofloxacin was applied to describe a 3 mg/kg intramuscular dose in lambs. The 6 healthy and 12 naturally infected with M. haemolytica lambs (Akkaraman, males weighing 10–15 kg and aged 2–3 months) were used in this study. In the marbofloxacin group, 6 healthy lambs received marbofloxacin. In the albendazole group after 2 weeks washout period, the same animals received marbofloxacin on 1 h after albendazole. In the diseased marbofloxacin group, 6 lambs naturally infected with M. haemolytica received marbofloxacin. In the diseased albendazole group, 6 lambs naturally infected with M. haemolytica received marbofloxacin on 1 h after albendazole. The marbofloxacin and albendazole were administered each as a single dose of 3 mg/kg intramuscular and 7.5 mg/kg oral, respectively, in the respective groups. Plasma concentration of marbofloxacin was measured with HPLC-UV and pharmacokinetic parameters were analyzed by non-compartmental model. Albendazole did not change the pharmacokinetic profiles of marbofloxacin in healthy and diseased lambs. However, M. haemolytica affected the pharmacokinetics of marbofloxacin in diseased lambs, AUC0–24/MIC90 ratio was not found to be higher than 125, but Cmax/MIC90 ratios was found to be higher than 10 for an MIC value of 0.25 μg/mL in all groups. The marbofloxacin dose described in this study may not be effective for the treatment of infections due to M. haemolytica in lambs, with MIC ≤ 0.25 μg/mL.