EN
Two groups of swine diseases were presented depending on their etiology. The first one included diseases caused, in each case independently, by one pathogenic microorganism and the second one contained diseases primarily caused by unfavorable environmental conditions. In this group as a consequence of the lowering of resistance against infection pathological action by facultatively pathogenic microorganisms took place. The paper concentrates on the two syndromes belonging to the second group of diseases: porcine post-weaning diarrhea (PPWD) and porcine respiratory disease syndrome (PRDS). In relation to PPWD, predisposing environmental factors connected with intensive technologies of swine production were presented. These were the following: a short period of lactation, too low temperatures in the weaning house, particularly during the two first weeks after weaning, and improper ventilation. As a consequence of these predisposing environmental conditions facultatively pathogenic E. coli strains proliferate in the intestine. Their pathogenic factors, special adhesions and enterotoxins participating in the pathogenesis of diarrhea were characterized. The role of rotaviruses as additional etiological agents of PPWD was also mentioned. Vaccination and antibiotic therapy were evaluated. As the next multifactorial disease, PRDS was characterized. Environmental factors contributing to lowering the resistance of the respiratory system to infection were noted. Some other contributing factors were: inadequate gilt replacement programs, large populations and too high a density of pigs, wide ranges of weaning ages, co-mingling pigs with mixed health status. Mycoplasma hyopneumoniae and PCV2 were mentioned as the main microorganisms participating in the etiology of the syndrome the PRRS virus, followed by other facultatively pathogenic microorganisms contributing to the development of the disease. Suggestions for general prophylactic measures were mentioned. Vaccination, particularly against PCV2, but also the two other noted microorganisms, was recommended. A figure containing general indications of potential risk factors in relation to both described syndromes was included in the paper.