CONVERSION OF CHRONIC STAPHYLOCOCCAL MASTITIS TO ACUTE GANGRENOUS MASTITIS AFTER NEUTROPENIA IN BLOOD AND BONE-MARROW PRODUCED BY AN EQUINE ANTI-BOVINE LEUKOCYTE SERUM

  • 1 January 1976
    • journal article
    • research article
    • Vol. 37  (8) , 885-890
Abstract
A stock strain of Staphylococcus aureus of mastitis origin, characterized by .alpha., .beta. and .delta.-toxins, was used to produce chronic mastitis of 20-300 days duration in 6 lactating mammary quarters of 4 cows. Early acute Streptococcus agalactiae mastitis was produced in 1 additional mammary quarter of 1 cow. Equine anti-bovine leukocyte serum (EABLS) was administered to all cows by continuous i.v. drip for 12-32 h. Neutropenia in blood and partial depletion of neutrophil reserve in bone marrow were produced. Chronic subclinical staphylococcal mastitis in 2 quarters of 1 cow changed to gangrenous mastitis by the 40th h after EABLS administration and led to death of the cow. The disappearance of neutrophil leukocytes from the milk was followed by uninhibited multiplication of S. aureus. Probably, staphylococcal leukocidins accelerated the destruction of neutrophils in the milk as S. aureus multiplication became intensified. In another quarter of the same cow that was infected with S. agalactiae, neutrophil leukocytes were present in milk as long as 3 days after their disappearance from blood and bone marrow. This may indicate the extravascular life-span of the neutrophil in the udder in mastitis. The 2nd cow died at the 16th h from the start of EABLS administration and at a time when gangrenous mastitis was in the initial stages of development. The S. aureus-infected quarters of the 2 remaining cows did not become gangrenous. Administration of EABLS to these 2 cows did not significantly reduce the numbers of neutrophil leukocytes entering the milk of the 3 S. aureus-infected quarters. Continuous diapedesis of neutrophil leukocytes into the milk in chronic staphylococcal mastitis apparently protects the gland against the development of gangrenous mastitis in the presence of a strain of S. aureus capable of .alpha.-toxin production.

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