Further investigations on the efficacy of a non-specific defence inducer evaluated in calves exposed to infectious bovine rhinotracheitis virus

Six calves were given the immunomodulator Baypamun and housed together with another six calves of which, three were experimentally infected with bovine herpesvirus-1 (BHV-1), whereas the remaining three served as untreated controls, The three experimentally infected calves as well as the three controls developed clinical signs of the typical acute form of infectious bovine rhinotracheitis (IBR). Of the calves treated with Baypamun, those that had only one injection of the immunomodulator, either at the start of the experiment (time 0) or 2 days later, underwent a much milder form of IBR and recovered in a shorter time than the experimentally infected calves or the controls. The calves that received four injections of the immunomodulator, i.e. at time 0 and subsequently for the next 3 days, remained healthy throughout the 30 days of observation. Moreover, the virus shedding by the Baypamun treated calves was significantly reduced. It was speculated that the use of an immunomodulator, eventually associated with a vaccination programme, would be a feasible approach to reduce significantly the onset of outbreaks of BHV-1, one of the main infectious agent initiating the respiratory disease in cattle. (C) 1998 Elsevier Science Ltd. All rights reserved.