Abstract: The purpose of this study is to examine changes in some biochemical parameters of treatment with tulathromycin in Montofon calves with pneumonia. For this purpose, 30 calves exhibiting clinical sings of pneumonia with fever, cough, lack of appetite, nasal flaring, mandibular lymph node enlargement, dyspnea and nasal discharge were studied. A control group of 20 healthy calves was also studied. Blood samples were collected from the healthy and diseased calves before and after treatment with Draxxin (Tluthromycin-Pfizer). Compared to the control group, Ca, K, total bilirubin, albumin, urea levels were affected (p<0.001) and Na (p<0.05) in the diseased animals and total protein, ALP, Glucose, Creatin levels were not affected in the diseased animals (p>0.05). Single dose tulathromycin therapy was characterized by significantly fewer treatment days, a higher response rate, significantly better reduction of pyrexia and fever and other pneumonia symptoms in calves requiring treatment.