Induction by endotoxin of the inflammatory response in the lactating and dry bovine mammary gland

Quarters of three lactating and three dry cows were infused with 10 micrograms endotoxin and the inflammatory response induced in the mammary gland was compared. The response of the dry glands was much less than that shown by the lactating glands. The swelling in the lactating quarters was severe after four hours and declined slowly; in the dry quarters the swelling was mild and transient. Antitrypsin levels, which reflect vascular permeability, were much greater in the lactating quarters, and the somatic cell counts were similarly much higher in the lactating quarters. One dry quarter gave no response other than a slight increase in antitrypsin after four hours.