Value of anatomopathological examination in goats with a positive comparative intradermal tuberculin test as part of a tuberculosis control programme.

Abstract

Background: Caprine tuberculosis is a chronic infectious disease caused by Mycobacterium bovis and Mycobacterium caprae. A tuberculosis control programme has been implemented using the comparative intradermal tuberculin (CIT) test. However, infection with Corynebacterium pseudotuberculsis and infection with or vaccination against Mycobacterium avium subspecies paratuberculosis (MAP) may have a negative impact on specificity. Therefore, a postmortem examination is necessary to verify the tuberculosis status of each animal where positive predictive value is low.

Methods: Thirty-seven CIT-positive goats from 14 herds with a previously tuberculosis-free status were slaughtered between 2015 and 2020, and postmortem examination was carried out at the School of Veterinary Medicine of Murcia.

Results: Anatomopathological examination ruled out the presence of tuberculosis lesions. In 23 of the goats, the anatomopathological examination revealed the presence of the paucibacillary form of paratuberculosis (associated with MAP infection), and in another six goats, Corynebacterium pseudotuberculosis infection was confirmed. Positive reactors have not reappeared in any of the herds in the annual CIT tests up to the year 2023.

Limitations: Only those herds that sent their positive animals to the veterinary school were included in the study. Participation in the postmortem analysis was not mandatory for farmers.

Conclusions: Anatomopathological examination is a useful, rapid and economically viable tool to determine the tuberculosis status of goat herds.