An overview of the impact of the environment on enzootic respiratory diseases in pigs

In intensive confined rearing systems worldwide, enzootic respiratory disorders are considered to be the most important diseases affecting growing and finishing pigs. In addition to various bacterial and viral pathogens, multiple environmental factors are generally involved. As actions have to be taken to reduce the incidence of these disorders, both the farmers and their advisers need to be aware of the environmental factors affecting the respiratory health of pigs in. order to implement appropriate preventive and control measures. This paper presents the main environmental factors which facilitate the introduction of respiratory diseases into farms and favour their spread and persistence within herds in intensive-confined systems. The transmission of respiratory pathogens between farms is mainly influenced by poor biosecurity, whereas the spread and maintenance of disease within herds is favoured by certain farm characteristics, management and housing conditions. These latter also determine the severity of clinical expression to a large extent. Although certain factors such as season and farm location are difficult to manipulate, a number of herd-factors can be directly and relatively easily handled by farmers to. ensure herd health maintenance.