Guinea pigs are quite susceptible to infection with either Mycobacterium tuberculosis or Mycobacterium bovis. They have been used extensively as a research model for human tuberculosis. Lesions occur most often in the parenchyma of the lung and adjacent lymph nodes. In addition, guinea pigs are susceptible to certain serovars of Mycobacterium avium complex, with lesions occurring in lymph nodes associated with the GI tract.
Tuberculin skin tests can be conducted by injection of purified protein derivative (PPD) of M bovis and of M avium (1:100 dilution containing 5,000 tuberculin units) at separate sites in the skin of the abdomen. The preferred injection site is 2 cm caudal to the xiphoid cartilage and 2 cm lateral on each side of the linea alba. The injection sites should be observed at 24 and 48 hours for induration and swelling. The presence of erythema at the injection site is of little or no importance.