In the present study, effects of enrofloxacin on biochemical, haematological and blood gas parameters were investigated. Changes in laboratory parameters were monitored during the treatment period. Enrofloxacin was administered (5 mg/kg intramuscularly, once daily) to 10 healthy dogs for 14 days. Acidosis and temporary increases in aspartate aminotransferase, indirect bilirubin, sodium, partial pressure of CO2 and mean corpuscular volume levels as well as decreased levels of inorganic phosphorus, ionized calcium, potassium, partial pressure of O2 and standard bicarbonate were observed. The results of this study suggest that these observed effects of enrofloxacin on blood gas parameters should be taken into consideration in long-term use of the drug.