The effect of physical activity on selected laboratory and clinical parameters in Maine Coon cats In order to observe and examine patterns of changes in certain laboratory and clinical parameters under the influence of physical activity in cats, sixteen untrained, healthy Maine Coon cats were observed in this study while undergoing physical activity on a treadmill. Determining clinical and laboratory parameters before and immediately after physical activity and also three times during 60-minute rest, body temperature, heart and respiration rate, and both lactate and creatine kinase concentrations showed significant changes and therefore they are discussed in more detail in this thesis. There was a constant increase of the average body temperature after performing physical activity, which lasted even during the 60-minute rest, after which a slight decrease in body temperature was observed. The value of the average respiratory rate increased immediately after performing physical activity, but a gradual decrease in respiratory rate was observed during the 60-minute rest period, during which the mean value reached approximately the same values as before the start of testing. Heart rate and lactate concentration were increased before performing physical activity, after which the lactate concentrations increased, whilst the heart rate decreased. However, during rest, a decrease in the direction of basal values was observed for both parameters. Creatine kinase concentration increased after performing physical activity. Physical activity affects mentioned parameters by increasing their values because they are all closely related to increased metabolism during exercise, and each of these parameters has its function in overcoming the physiological stress. Emotional stress caused by environmental factors can affect cats to such an extent that it significantly increases the heart rate and lactate concentration before performing the exercise itself.