Background and Aim: Respiratory diseases in young cattle are among the significant cattle pathologies that cause considerable economic damage globally. For the treatment of respiratory diseases, coformulated drugs that increase general nonspecific resistance, exhibit adaptogenic and anti-inflammatory properties, and normalize metabolic processes in animals are currently being used. The aim of our study was to investigate the therapeutic efficacy of the complex drug "gentaminoseleferon", used in the treatment of respiratory diseases in calves, especially in Mycoplasma dispar infection.

Materials and Methods: The animals were divided into three groups. Calves with the first clinical signs of respiratory pathology were randomly divided into two groups. The first experimental group (n=5) was intramuscularly injected with sulfetrisan at a dose of 5-10 mL/animal once per day for 7 days. The second experimental group (n=5) was given gentaminoseleferon at a dose of 1 mL/10 kg of body weight once per day for 7 days. The drugs were not used in the control group, the "healthy animals (n=5)". Blood samples were taken 10 days before and after treatment and compared between the experimental and healthy calves. The changes in the hematological and biochemical parameters of blood and serum were evaluated.

Results: During the recovery process of animals in the experimental groups, a normalization of the hematological and biochemical parameters of blood and serum was noted. Interestingly, in calves of the second experimental group, an increase in the total serum protein content by 2.2% (p<0.05) was recorded in comparison with the first group. The second group, furthermore, showed an increase in Vitamins A, E, and C concentrations by 13.5% (p<0.05), 11.9% (p<0.005), and 15.1% (p<0.0005), respectively, as well as in zinc and iron concentrations by 4.1% (p<0.05) and 9.3% (p<0.0001), respectively. These findings indicate a more pronounced decrease in the inflammatory process in the respiratory system and intensive restoration of metabolism, thereby establishing the high therapeutic efficacy of gentaminoseleferon.

Conclusion: Gentaminoseleferon was proven highly effective in the treatment of calves with respiratory illnesses and in restoring homeostasis in the organisms of animals after treatment, as indicated by the normalization of morphological and biochemical blood parameters with a reduction in the recovery time.

Keywords: blood parameters, calves, gentaminoseleferon, Mycoplasma dispar, respiratory diseases.