The pathogenesis of experimental Escherichia coli mastitis in newly calved dairy cows.
Experimental infections of the mammary gland of newly calved cows with 500 serum resistant Escherichia coli produced a very severe form of mastitis when compared with animals in mid-lactation. Ten hours after infection the bacteria had multiplied in the milk to very high numbers (10(6)--10(7)/ml) and the animals showed signs of pyrexia, anorexia and diarrhoea. Initially the gland and milk showed little or no clinical signs of mastitis, but later the secretion became a viscous, serous fluid with little or no casein or fat. A delay in diapedesis of neutrophils into the gland appears to be the reason for the peracute state and lack of clinical signs. This form of pathogenesis may produce a paradoxical situation where the most severe cases of E coli mastitis cannot be diagnosed at a stage early enough for the animal to respond to therapy.
D000818:Animals; D002417:Cattle; D004926:Escherichia coli / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000382:microbiology / Q000473:pathology; D008414:Mastitis, Bovine / Q000382:microbiology / Q000473:pathology*; D008892:Milk / Q000382:microbiology; D049590:Postpartum Period; D011247:Pregnancy