Comparison of Treatments for Caseous Lymphadenitis in Small Ruminants: Opening, Draining and Flushing Versus Intralesional or Parenteral Tulathromycin
The objectives of our study are to evaluate and compare treatments of caseous lymphadenitis in small ruminants, and to investigate in vitro susceptibility of Corynebacterium pseudotuberculosis to tulathromycin.
Client-owned cases are enrolled based on the presence of a peripheral, subcutaneous mass and are randomly assigned to one of three treatment groups. From all cases, lesions are aspirated for bacterial culture and antimicrobial susceptibility, and blood is collected for serum hemolysin-inhibition testing. Treatment groups are as follows: opening, draining and flushing the lesions (A), intralesional tulathromycin (B), and subcutaneous tulathromycin (C). Animals are discharged to owners with specific instructions regarding biosecurity and parameters that warrant re-examination or constitute treatment failure. All cases are re-examined approximately one month from enrollment, unless treatment failure is observed. If lesions are unresolved, they are re-cultured, opened, drained and flushed (A). Follow-up serology is also performed at this time.
Thirty-two cases have been enrolled, of which 24 possessed culture positive C. pseudotuberculosis lesions. Minimum inhibitory concentrations for C. pseudotuberculosis isolates range from < 1-2 µg/ml, with 71.4 % < 1µg/ml. Of 24 culture positive lesions, 20 were resolved in one month. Of the treatment failures, 1 was Group A, 1 was Group B and 2 were Group C.
Data so far indicate that C. pseudotuberculosis isolates from clinical cases are sensitive to tulathromycin, although there are no validated breakpoints on which to make that determination, and that there may be acceptable alternative treatments of caseous lymphadenitis rather than opening, draining and flushing the lesions.