Effect of prostaglandin synthetase inhibitors on mammary blood flow during experimentally induced mastitis in lactating goats.

Mammary blood flow (MBF) was recorded chronically in lactating goats by means of an electromagnetic flow probe. Experimental mastitis was induced by intramammary injection of E. coli lipopolysaccharides. Control mastitis experiments were accompanied by a significant increase in MBF characterized by 2 conspicuous peaks, by fever, increased heart rate, swelling, heat and pain of the gland, and increased chloride in milk. The non-steroidal anti-inflammatory drugs suprofen, indomethacine and flurbiprofen were potent antipyretics during mastitis but had only little effect on the biphasic MBF pattern. Indomethacine induced a strong and long lasting vasoconstriction in the udder. MBF peak I was quantitatively unaffected although flurbiprofen was able to delay its appearance. All drugs partially suppressed MBF peak II, this being most significantly with flurbiprofen. None of them prevented either swelling of the gland or high milk chloride but all inhibited pain in the gland. MBF peak II may be partially induced by the decrement stage of fever. Locally formed prostaglandins play little or no role in the genesis of MBF peak I but may be involved in MBF peak II.