A Trial in Goats of an Inactivated Staphylococcal Polyvalent Somatic Antigen Vaccine Against Mastitis

Abstract

SUMMARY The potency of a staphylococcal polyvalent somatic antigen vaccine against mastitis in the goat was examined. A preliminary pathogenicity trial with six of the vaccine strains revealed that none was sufficiently pathogenic to be used as a challenge organism. Therefore strain BB (phage type 78), a proven udder pathogen, was used as the test strain, and was inoculated into one side of the mammary gland of fifteen vaccinated and eight non-vaccinated goats. Measurements were made of body temperature, visible and palpable induration of the udder, milk yield, milk leucocyte count, bacterial count and the degree of histological abnormality in infected tissue. All the vaccinated animals developed mastitis which varied in severity from mild to gangrenous. All the non-vaccinated animals except one developed mastitis of the same range of severity. There was no significant difference in the relative numbers of animals in either group that developed gangrenous, generally severe, focally severe, or mild mastitis. There was no significant difference in the relative loss of function of the mammary gland in either group, neither was there a difference in the degree of bacterial invasion of the mammary gland, nor in the number of leucocytes excreted in the milk. Twenty days after vaccination one animal developed naturally acquired gangrenous mastitis due to a strain of Staphylococcus aureus other than the challenge strain.