Incidence of tonsillar lesions caused by Tonsillophilus suis and Actinomyces sp infection in swine.

The tonsils of ten fattening pigs were compared with those of ten breeding sows to determine the relative incidence of Tonsillophilus suis and Actinomyces sp lesions. Macroscopic observation revealed mildly focal upheavals on the tonsillar mucosal surfaces of two of the breeding sows. In tonsillar slices from both pig groups, tiny nodules containing sulfur granules were found. Histopathologically, the T. suis and Actinomyces sp lesions were noted as tonsillar crypt abscesses in both pig groups, and granulomas due to T. suis were seen in the breeding sows. T. suis showed larger 'club-shaped' structures than Actinomyces sp, characterized as clubs showing a broom-like structure with degenerated central thalli. Breeding sows are known to have a higher incidence of tonsillar T. suis lesions than fattening pigs, and in this study, those fattening pigs showing greater propensity to infection by Actinomyces sp also showed a mixed infection with T. suis that produced the tonsillar crypt abscesses. In addition, it is known that in breeding sows, the T. suis lesion develops from a crypt abscess into a granuloma.