No abstract

An outbreak of tuberculosis (TB) caused by Mycobacterium bovis in a llama herd is described. Over a 25-month period, a total of 70 llamas were selected for postmortem examination using four distinct criteria: clinical suspicion of disease (15 animals), positive tuberculin skin test result (three animals), antibody positive using a novel serological test (Rapid Test, 54 animals) and elective cull (five animals). Some animals qualified on more than one criterion. Gross lesions of TB were detected in 15 animals, with lung and lymph node lesions consistently observed. Samples were collected from 14 of 15 animals with visible lesions as well as those with no visible lesions, for histopathology and mycobacterial culture. All 14 llamas with visible lesions had caseonecrotic granulomatous lesions associated with acid-fast bacteria and variable mineralisation, and M bovis was isolated from 13. There were no histopathological lesions of TB in llamas with no grossly visible lesions, and M bovis was not isolated from any of these. The predictive value of suspicious gross lesions at postmortem examination was therefore high in the herd. Molecular typing results indicated that the outbreak was caused by a single strain likely to have originated from a local reservoir, probably cattle or wildlife. Antemortem indicators of infection assisted control of the outbreak, but no single test accurately identified all TB cases. Visible lesions were detected in nine of 15 llamas with clinical suspicion of disease, in two of three that had positive tuberculin skin test results and in 10 of 54 that were antibody positive; there was none (zero out of five) in llamas that were electively culled.

No abstract

No abstract

No abstract

No abstract

Antibiotic dry cow therapy (ADCT) is a crucial component for the control of contagious mastitis pathogens as part of a herd's mastitis control policy and recent research has again highlighted the excellent cure rates achieved with ADCT, despite ‘apparent’ cure rates across the dry period averaging much lower than those published. However, following the control of the classic contagious mastitis pathogens, environmental pathogens such as Escherichia coli and Streptococcus uberis have become significantly more important and have resulted in a shift in emphasis at drying off, away from identifying those cows with a persistent infection towards protecting those without. This means there are two clear roles for any dry cow therapy, i.e. the cure of existing infections and the prevention of new ones, giving rise to a challenge for veterinary herd health advisors. This should lead to an increased awareness of the importance of taking an individual cow approach to dry cow therapy — moving away from ‘blanket’ ADCT approaches, using internal teat sealants and products with extended Gram-negative activity to protect against new infections and regularly reviewing the use of ADCT in herds as part of prescribing antimicrobials responsibly.