[Infection-limited disease factors in cattle].

The following infectious diseases of cattle can be included in the group of the so-called infectious 'factors disease': certain respiratory diseases, in particular enzootic bronchopneumonia (EBP, 'shipping fever'), trichophytia, some parasitic skin diseases and internal parasitoses, certain types of calf enteritis, special forms of mastitis and of genital infections and possibly others. As is discussed in the paper EBP is a typical multifactorial infectious disease in cattle. The role of Pasteurella spp. in the pathogenesis of EBP is shown on the basis of recent investigations in young beef cattle. When performing research on such diseases there arises the following difficulty: for biological, technical and financial reasons it is hardly possible to test the whole spectrum of the viral and bacterial germs presumably involved as well as the whole complex of influencing factors in the animal and in its environment. Such restrictions therefore reduce the value of clinical or experimental studies. Nevertheless, the systematic investigations of such factors which possibly are significant, have proven useful. Some examples are mentioned.