With a recent rise in the number of TB cases found on US dairies in a number of states, and the downgrade of California’s TB status, it seems a good time for a tune up on TB testing protocol. As an accredited veterinarian you must follow the guidelines below:
Handling tuberculin
Check the expiration date -
Store in a refrigerator
Do not freeze, and avoid sunlight
Do not draw up ahead of time
Throw away unused portions – oxidizes quickly!
Identification
Record the official identification of every animal tuberculosis tested
Official identification includes an official eartag or a registration tattoo
Injection
Use 1 ml. syringe with 26 g 3/8” needle
Inject 0.1 ml. intradermally in the caudal fold – get a “bleb”!
If you inject, you read (remember which side)
Do not vaccinate or treat cows on injection day
There is no meat or milk withdrawal time for tuberculin
Reading the test
Palpate every injection site you injected
All animals injected must be read and recorded on official forms
Read the test at 72 hours post injection ± 6 hours
ANY swelling is a positive response (check suspect box)
Report any responders immediately to the office of the State Veterinarian and provide a copy of the test records
1-5% false positive rate is expected - causes include M. avium subsp paratuberculosis, M. avium, and other soil-borne Mycobacterium
State/Federal veterinarians must apply the CCT test on any responders within 10 days of injection, or must wait 60 days.
Mail white and green copies to the office of the State Veterinarian within five days of reading the test. If you have any questions, please contact the State Veterinarian at 503-986-4680.
Your efforts in carrying out effective TB surveillance are appreciated.
