PATHOMORPHOLOGICAL CHANGES OF THE LYMPH NODES OF PIGS AT DIFFERENT STAGES OF DEVELOPMENT OF CLINICALLY EXPRESSED

Due to the multifactorial nature of the occurrence, multisymptomy of manifestation, circovirus infection of type II pigs has a significant impact on the economy of pig farms around the world. Pathomorphological changes in the body of pigs with PCV2-infection occur moderately and in stages, as a result of the simultaneous launch of a set of mechanisms to counter the causative agent of the disease, resulting in the formation of a whole spectrum of reactive and pathological processes. The determination of structural and functional peculiarities of pathomorphological changes of lymph nodes of pigs at different stages of development of clinically expressed PCV2-infection was carried out. The work was carried out in pig farms of Ukraine, with intensive technology of pig rearing, at the department of normal and pathological anatomy of agricultural animals and the Scientific and Research Center for Biosafety and Environmental Control of the Agroindustrial Complex Resources of Dnipro State Agrarian and Economic University. For pathomorphological studies, animals were selected with clinical signs of active PCV2-infection (in 1 ml of whole blood of which contained more than 10⁷ copies of the PCV-2 virus equivalent gene) and also piglets with positive optical density of specific antibodies (Ig G and Ig M) in serum blood. It was established that the morphometric parameters of the lymph nodes during the development of the circovirus process tend to increase significantly, which is especially pronounced at the stage of active (chronic) PCV2-infection. The maximum relative area of the lymphoid parenchyma is observed in the lymph nodes of pigs at the stage of early active (subacute) PCV2-infection. Against the background of a decrease in the relative area of the lymphoid tissue, the relative amount of connective tissue is markedly increasing, which is especially pronounced in somatic lymph nodes. Among the individual cellular areas of the parenchyma during the development of the infectious process, in the stage of active (chronic) and late stages PCV2-infection, most pronounced decreases the relative area of the specialized cellular regions  –  the deep cortex and lymph nodes