Monitoring of sows’ health is the key to preventing and controlling diseases in sows, and it guarantees optimal rearing conditions for piglets. The aim of this study was to investigate the relationship between the health status of sows shortly after parturition, and to analyze thermographic images of the mammary gland and the sows’ performance. Clinical examination of a total of 513 db.Viktoria hybrid sows was bundled individually using a modified score system. According to this, animals were divided into three health classes: healthy, clinically suspicious, and diseased. Simultaneously, the mammary glands were investigated by infrared thermography. Total born piglets (TBP), number of piglets born alive (NBA), and the daily weight gain of the piglets were significantly lower in the diseased group (p < 0.05). Regarding the results of the thermographic images of the mammary gland, significantly higher mean value of the warmest pixels was found in the diseased group (38.3 °C ± 0.57), while the significantly lowest value was reported in the healthy group (37.2 °C ± 0.54; p < 0.05). The results of this study show that thermography of the mammary gland at birth contains information that can help to identify diseased animals whose disease has negative effects on their piglets.