• Inflammation occurred in the udder despite only infusion of bacterial components into the uterus.
• Non-bacterial mastitis was found for the first time.
• Results can lead to a potential decrease in unnecessary antibiotic use for treating mastitis.

Mastitis is a common disease of dairy cows that is usually thought to be caused by bacterial invasion and infection of the udder. However, since bacteria are sometimes not detected in milk obtained at the time of mastitis, we conceived the idea that mastitis may be caused by reasons other than infection by live bacteria. Since bacterial infections occur frequently in the uterus, we expected that components of uterine bacteria might migrate to the udder through the blood stream and subsequently cause mastitis. A study was conducted to test this hypothesis.

Using goats as model animals, we infused lipopolysaccharide (LPS), a component of the bacteria, into the uterus daily for one week, resulting in a decrease in milk yield and an increase in somatic cell count (SCC, an indicator of inflammation). The concentration of inflammatory cytokines in milk was also significantly increased by intrauterine LPS infusion. These findings indicate that intrauterine infusion of bacterial components can cause mastitis. In other words, there is a possibility of mastitis not caused by bacterial infection in the udder. In such cases, antibiotic treatment becomes unnecessary, thus making a significant contribution to anti-antibiotic therapy.

In the future, we hope to find a simple method to correctly diagnose whether mastitis is caused by bacterial infection or not, and to reduce the unnecessary use of antibiotics.

• Journal: Theriogenology (2022) 193: 87-92
• Title: Effect of Repeated Intrauterine Infusion of Lipopolysaccharides on Mastitis in Goats. 
• Authors: Jaisue Jirapat, Nii Takahiro, Suzuki Naoki, Tsugami Yusaku, Isobe Naoki
• DOI: doi.org/10.1016/j.theriogenology.2022.09.009