Respiratory diseases in pigs caused by the influenza A virus pose a serious threat to pig farming as they negatively affect productivity and overall health of the animals. Co-infections with bacterial pathogens complicate the clinical condition of pigs, highlighting the importance of modern monitoring methods for improving diagnosis and control of these diseases. A pathological monitoring study of lung lesions in pigs was conducted from 2022 to 2024 on 10 pig farms in Kyiv, Vinnytsia, Cherkasy, and Chernihiv regions. Serum diagnostics for antibodies to the influenza A virus in piglets were performed using the IDEXX Influenza A Virus Ab Test Kit. The farms were divided into two groups, each consisting of 5 farms. The first group, serologically positive, included farms where antibodies to influenza were detected in the blood of piglets. The second group, serologically negative, consisted of farms where antibodies to the influenza virus were not found in the blood of piglets. The assessment of the pathological condition of the lungs was conducted at meat processing enterprises in pigs aged 6-7 months, using the Ceva Lung Program (CLP) and the SPES methodology for evaluating pleuritis. Statistical analysis of the results was carried out using the CLP software, which takes into account the degree of lung damage. The results showed that on farms where pigs were serologically negative, the number of cases of lung lesions due to bronchopneumonia decreased by 14.2% (p<0.001) compared to positive farms. The percentage of lung surface affected by bronchopneu monia on healthy farms was 21.8% lower (p><0.001) compared to unhealthy ones. The level of broncho pneumonia on farms without the influenza virus was also significantly lower, as evidenced by a 23.4% > <0.001) compared to positive farms. The percentage of lung surface affected by bronchopneumonia on healthy farms was 21.8% lower (p<0.001) compared to unhealthy ones. The level of bronchopneumonia on farms without the influenza virus was also significantly lower, as evidenced by a 23.4% reduction in the EP index (p<0.05). On farms that were serologically negative for influenza, a decrease in the level of pleuropneumonia was observed, with the ARR index being 25.2% lower (p<0.05) com pared to farms with the virus.> <0.05) compared to farms with the virus. The study of the lung condition in pigs slaugh tered on farms with different epidemic statuses regarding influenza revealed significant differences in lung lesion indicators. On farms that are free of influenza virus, a substantial decrease in the frequency of lung lesions in piglets was recorded. This indicates the importance of controlling the spread of the influenza virus in pigs to improve the overall health status of the animals. Effective monitoring and control of the virus can reduce the risk of respiratory diseases, which in turn will contribute to increased productivity and economic benefits for pig farming.

Key words: pigs, lungs, swine influenza, pneumonia, healthy and unhealthy farms, monitoring, diagnosis.