Treatment of the following specified infections of the respiratory tract and the alimentary tract caused by micro-organisms susceptible to doxycycline. Pre-ruminant calves: – Bronchopneumonia and pleuropneumonia caused by Pasteurella spp., Streptococcus spp., Arcanobacterium pyogenes, Histophilus somni and Mycoplasma spp. Pigs: – Atrophic rhinitis caused by Pasteurella multocida and Bordetella bronchiseptica; – Bronchopneumonia caused by Pasteurella multocida, Streptococcus suis and Mycoplasma hyorhinis; – Pleuropneumonia caused by Actinobacillus pleuropneumoniae. Chickens (broilers, breeders), turkeys (broilers, breeders): – Infections of the respiratory tract caused by Mycoplasma spp., Escherichia coli, Haemophilus paragallinarum and Bordetella avium; – Enteritis caused by Clostridium perfringens and Clostridium colinum.