In our dissertation, we analyzed data from laboratory studies of abortions in cows for the period from 2014 to 2018, applied a comprehensive diagnostic approach using modern diagnostic devices and methods (PCR-RT, MALDI-TOF), presented the etiology of abortions in cows in Ukraine for the period from 2019 to 2022, the prevalence of abortions in cows, and established pathoanatomical and pathohistological changes caused by N. caninum in aborted fetuses and fetal parts of placentas of cows. According to the results of the analysis of the molecular diagnostics laboratory of LLC "Center for Veterinary Diagnostics" data on infectious agents detected by PCR in cases of abortion in cows from 18 regions of Ukraine, it was found that the largest percentage falls on bacteria – 43,43 %, then on mixed infections (different in composition of the association of viruses, bacteria and protozoa) – 31,32 %, viruses – 23,23 % and protozoa – 2,2 %. After analyzing the obtained spectrum of microorganisms, little-studied infectious agents in Ukraine were identified - N. caninum, BHV-4, Coxiella burnetii, which cause or may cause abortion in cows. We investigated 162 cases of abortion in cows from 65 farms from 14 regions of Ukraine, using comprehensive diagnostics (pathological, histological, bacteriological, molecular genetic (PCR-RT) studies). The etiology of abortion in cows was established in 24,07 %, the probable etiology was established in 29,02 %, while in 46,91 % of cases the etiology was not established, which coincides with the global trend in the diagnosis of abortion in cows. Abortion with established infectious etiology in 30,77 % of cases was caused by bacteria, in 10,26 % - by viruses, in 28,21 % - by protozoa and in 30,76 % - by mixed infection. Abortion with probable infectious etiology in 10,64 % of cases was caused by bacteria, in 25,53 % - by viruses, in 34,04 % - by protozoa and in 29,79 % - by mixed infection. The most common infectious agents isolated from aborted fetuses, fetal parts of placentas and vaginal swabs of cows during the study period were BHV-4 detected in 11 and N. caninum – in 9 regions of the country. W. Among the pathological changes in aborted fetuses, the most frequently recorded were: liver dystrophy, congestive phenomena in the brain, necrotic-inflammatory changes in skeletal muscles and liver, hemorrhages in internal organs, and in the fetal parts of the placenta - edema and placentitis. After analyzing the data, we obtained, we established the prevalence of infectious agents for 2014-2022, which were isolated from pathological material during abortion in cows. The most common were: Mycoplasma spp. (15 regions (2014-2018)), BHV-4 (14 regions), N. caninum (10 regions (2017-2022)), BVDV (9 regions), Coxiella burnetii (8 regions), BHV-1 (7 regions), Salmonella spp. (6 regions). It was established that most abortions caused by N. caninum occurred at 4-6 months of gestation. During external examination of aborted fetuses, we found, individually, hyperemia of the skin and hemorrhages on the skin throughout the body, mummification of the fetuses. In most cases, autolysis of aborted fetuses and fetal parts of placentas was noted, and in some cases, placentitis and edema of the fetal parts of placentas. During internal examination of aborted fetuses, in addition to changes characteristic of autolysis, changes of various nature were detected in the brain, skeletal muscles, heart, lungs, liver, spleen, and kidneys. In aborted fetuses and fetal parts of placentas from which N. caninum was isolated, the following pathohistological changes were most often detected: focal gliosis and perivascular lymphoid cell infiltrates in the brain; focal or diffuse lymphoid cell infiltration of the heart wall and skeletal muscles; periportal lymphoid cell infiltrates of the liver stroma; focal necrosis of the mucosa and lymphoid cell infiltration of the mucosa of the fetal part of the placenta.
