The invention relates to 8a-azalides which are used for the treatment and prevention of respiratory and enteral infections in animals, in particularly in cattle and pigs. The compounds are applied in a therapeutical and prophylactic effective quantity ensuring a level of antibacterial activity in the organism in the animals sufficient to inhibit the bacterial pathogenous agents of respiratory infections: Pasteurella haemolytica, P. multocida,Haemophilus somnus and Mycoplasma spp. in cattle, and Pasteurella multocida, Actinobacillus pheuropneumoniae and Mycoplasma spp. in pigs.