Synergistic hemolysis-inhibition titers associated with caseous lymphadenitis in a slaughterhouse survey of goats and sheep in Northeastern Brazil.

A survey of caseous lymphadenitis was conducted at a goat and sheep slaughterhouse in Northeastern Brazil One hundred and fifty-eight goats and 43 sheep were examined for the presence of abscesses, with bacterial culturing of purulent material to define the etiological agent. Blood was collected simultaneously for determination of serological titer via the synergistic hemolysis-inhibition test which measures antibodies to an exotoxin of Corynebacterium pseudotuberculosis. Thirteen and nine-tenths percent of the goats had abscesses, with a high proportion having mediastinal or pulmonary lesions (9.5%). Two sheep had abscesses, both with internal organ involvement. Corynebacterium pseudotuberculosis was the most frequently isolated organism. Of 22 goats with abscesses, 20 were positive via the synergistic hemolysis-inhibition test. Both of the sheep with abscesses had positive synergistic hemolysis-inhibition titers. The proportion of serological reactors was greater than the proportion of animals with abscesses. The synergistic hemolysis-inhibition test may be detecting subclinically infected animals.