Outbreak of infectious bovine rhinotracheitis in a farm of dairy cows

The aim of the, study was,to determine the etioloical factor of an outbreak of cattle sickness with symptoms from respiratory tract and abortions in pregnant bows on a dairy farm. The disease appeared after the arrival on the farm of 5 imported heifers from Denmark, Germany and the Netherlands. The diagnosis was based on the clinical examinations Of the animals, sections, as well as histopathological, bacteriological, serological and virological tests. The virological examination of nasal swabs and internal organs revealed a BHV1. Moreover, a serological examination done by ELISA method of 25 sera revealed antibodies specific for this pathogen in 24 samples. Pasteurlle multocida was isolated in 6 out of 25 nasal swabs by bacteriological examinations. The observed changes in the internal organs from sections and in histopathological preparations were characteristic for secondary infections by this bacteria. Analysis of the results indicated that the etiological factor of the outbreak, was infection by BHV1 with a secondary infection by Pasteurella multocida. The disease probably resulted, from the reactivation of a latent infection of BHV1 in one of the imported heifers.