TUBERCULIN TEST IN EXPERIMENTALLY SENSITIZED SHEEP (OVIS ARIES)

ABSTRACT

This study aimed to establish the reference values for the interpretation of the skin test in sheep experimentally inoculated with standard strains of Mycobacterium bovis AN₅ and Mycobacterium avium D₄, and evaluated the clinical manifestations induced by the intradermic immune-allergic response to tuberculin. Thirty healthy sheep were separated in three groups: A) sensitized with M. avium, n = 10; B) sensitized with M. bovis, n = 10; and C) control, n = 10, which were injected with saline solution. After 45 days of inoculation, the Comparative Cervical Test (CCT) was evaluated by the variation of dermal thickness measured by skinfold calipers carried out at the following moments: before the administration of tuberculin (PPD – purified protein derivative) and at 12, 48, 72 and 96 hours after PPD inoculation. In regard to the bovine PPD, the Single Cervical Test (SCT), observed at 72 hours (± 6 hours) post-tuberculinization (p.t.) the response was considered as: positive, when skinfold thickness was equal or greater than 2.40 mm; inconclusive, when skinfold thickness was between 1 and 2.40 mm; and negative, when skinfold thickness was lower than 1 mm. Analyses of the results of the CCT performed at 72 hr p.t.

KEY WORDS
Tuberculosis; diagnostic; Comparative Cervical Tests; Single Cervical Test; sheep