This study aimed at understanding the clinical signs and pathological changes in the weaner and grower pigs that were affected by the porcine reproductive and respiratory syndrome (PRRS). The first clinical signs observed in both pig categories were fever, anorexia, erythema and rhenorea. In the weaner pigs, the typical signs were constipation or diarrhea and cyanosis. In the growers, dispnea, coughing, diarrhea and ear cyanosis were observed. The main macro-changes in both pig categories were recorded in the lungs: necrosis, hepatised, dark red colored, the cut surface was concave and dry. Changes in other organs were as follows: enteritis, hemorrhages, flacid heart, swollen liver... The microcospic changes were found mainly in the lungs: infiltration of inflammatory cells, exudate in the alveols
blood cell infiltration in the kidneys
disappearance of the septums in the spleen and infiltration of the blood cells
detachment of the enteric mucosae, destruction of the villi. Using the immunofluorescent technique the presence of the PRRS virus was confirmed in the studied organs. This technique helped confirm the disease diagnosis and thus helped applying effective measures and reducing the losses.