Predisposing factors inducing ovine respiratory complex in intensive-reared lambs.

• Main implicated bacterial species from the ovine respiratory complex can be isolated from the respiratory tract of healthy sheep. • Stressor factors, including the management practices performed in the farm, may increase the incidence of ovine respiratory complex in the herd. • The understanding of the main factors involved in each case in the development of the ovine respiratory complex is the key point for an effective control of the disease. The ovine respiratory complex is an etiologically complex disease, occurring as a result of an interaction of the infectious agents with the host defence mechanisms, which are often compromised by environmental and management factors. There may be several combinations of contributors that are sufficient to produce disease, with variable importance of an individual factor with the presence of other variables. The present article will review predisposing factors that lead to the emergence of ovine respiratory complex. These factors will be grouped into concurrent infections, host, environmental and management aspects. This manuscript will be completed by other four articles included in the same number of this journal, all of them dealing with different approaches to ovine respiratory complex disease. [ABSTRACT FROM AUTHOR]