Pathology of acute experimental Actinobacillus seminis mastitis in ewes

Sequential pathological changes were studied for 9 days after inoculating Actinobacillus seminis in the mammary gland of sheep. The inoculated mammary glands became enlarged (2 to 4 times normal), turgid or consolidated and contained creamy or greenish-yellow viscid contents. A seminis was isolated from all inoculated udders at necropsy. Microscopically, the reaction in the udder to A. seminis may be divided into 4 overlapping phases; acute purulent, subacute purulent, necrotising, and proliferative. It was concluded that A. seminis was pathogenic for the ovine mammary gland, the clinical and pathological findings were nonspecific, and that A. seminis could survive within ovine mammary tissue for at least 9 days after inoculation.