Do I Have To Have A Tb Skin Test For Vet Tech

Tuberculosis

Last Modified: Jun 2, 2020

Bovine tuberculosis (TB) is a contagious, infectious, communicable disease of animals and humans acquired by Mycobacterium bovis. Information technology is unremarkably a chronic, debilitating disease just occasionally may assume an acute, rapidly progressive form. TB is a widespread zoonosis of global magnitude and affects virtually all species of vertebrates. Disease is spread by direct contact, inhalation of droplets expelled from infected lungs, and ingestion of contaminated feed or milk. All accredited veterinarians must immediately report every suspected or diagnosed bovine TB case promptly to both the Assistant District Managing director and the State Animal Health Official.

Testing

Diagnosing TB in live animals depends on using an effective testing technique with an intradermal injection of tuberculin obtained through your State animal health official or APHIS –VS District Office. Several varieties of tuberculin are produced. Nonetheless, use only bovine purified protein derivative tuberculin (PPD bovis) licensed by USDA for official testing. See tabular array 1 for tuberculin test requirements for different species of animals.

Tabular array 1 – Tuberculin test data for various animate being species

Species	Dose and Blazon	Site	Read test visually and palpate
Cattle & Bison	0.1 mL PPD bovis	Caudal Fold	72 h +/- 6h
Horses	Not reliable
Sheep & Goats	0.1mL PPD bovis	Caudal Fold	72 h
Swine	0.1mL PPD bovis	Base of Ear or Vulvar lips	48 h
Poultry	0.05 mL avian	Wattle	48 h
Exotic Bovidae	0.1mL PPD bovis	Midcervical	72 h
Deer, Elk & other Cervidae	0.1mL PPD bovis	Midcervical	72 h
Camelidae	0.1mL PPD bovis	Postaxillary Region	72 h

Note: TB testing and examination event interpretation for many exotic species (such every bit some zoo animals) are not nevertheless developed or reliable. For interstate motility of these animals, contact the State animal health official in the State of destination for the TB-testing requirements (if whatever) for these species.

Because the tuberculin test is based on an immune response, the animal being tested should not concurrently exist receiving other medications, vaccinations, or anthelminthic drugs. These agents may temporarily affect the immune system and influence the issue of the tuberculin test. This also means that sick animals may non be injected even if they are not being medicated or treated in any style. In add-on, tail-haemorrhage is non recommended for other diagnostic procedures (e.chiliad., brucellosis, Johne'southward disease) at the time of tuberculin-examination injection in cattle or bison because tail-bleeding may interfere with test estimation.

Veterinarians are legally responsible for properly conducting and evaluating the results of tuberculin tests. Therefore, perform the test yourself; do non delegate the responsibility to a technician. For TB testing in species other than cattle or bison (e.g., cervidae), contact your Country animate being health official or APHIS –VS District Office for additional guidance.

Instructions for Testing

Stride 1: Forms—

Complete VS Form half dozen–22, Tuberculosis Test Record. (See appendix D for an case of this form and instructions for completing information technology.)
Identify the fauna on the form by its official identification as outlined in the section entitled "Current Animal Identification."

All cattle and bison tested shall be individually identified by official eartags. Such identification must be recorded in its entirety on the examination tape at the fourth dimension of injection and must be confirmed at the time of observation.
Additional identification (such as bangle tags, non-official metallic ear tags, neck concatenation numbers, tags, brands, horn numbers, and names) should too be recorded on the test record as supplemental information, simply must never be used equally the sole method of identification.
When cattle and bison have been tagged with more than 1 official ear tag, all ear tag numbers must be recorded in their entirety.
The breed, sex, and approximate age in years of each animal tested must be recorded in their entirety on the examination record. Abbreviations such equally C=Calf or A=Adult are not to be used.
The owner should be informed of the number of animals injected, and advised to restrict them to the premises until the test is completed.

Step 2: Supplies—

Tuberculin. Use USDA-Veterinarian Services approved PPD Bovis tuberculin (run across tabular array 1). Check the expiration engagement to exist certain that the tuberculin is still valid.
Syringe. Apply disposable 1.0 cc plastic tuberculin syringe.
Needle. Employ a 26-judge, 3/8-inch-long needle; a larger guess and longer or shorter needle might permit the tuberculin to leak from the injection site. A new needle must be used for each animal.

Step 3: Injection of Tuberculin— All cattle and bison tested must exist sufficiently restrained to let conscientious application of the tuberculin injection(southward), correct reading of animate being identification, and careful observation and palpation of the injection sites. No test should be practical or observed without having the animate being restrained in a satisfactory manner. Nose tongs are no longer used by APHIS regulatory personnel.

In cattle and bison, injections should be fabricated about ii to three inches distal to the base of operations of the tail. Rest the caudal fold on the forefinger exposing the area exterior the hairline in bare skin near the center of the caudal fold.
Note scars, defects, and anomalies of the pare in this expanse on VS Form 6–22 so that they will non be dislocated with possible test reactions at the time of reading.
Utilise the caudal fold on either side of the tail; however, note which side you injected.
Clean the expanse to be injected, but exercise not use alcohol because information technology may be irritating to the skin.
Grasp the caudal fold between the thumb and index and middle fingers to stabilize information technology.
Carefully insert the needle to its full length between the superficial layers of the skin; withdraw information technology slightly and deposit 0.one mL of tuberculin.
A small bleb should appear in the pare at the end of the needle.

Note: Information technology is important to establish a consequent injection technique (i.due east., all animals should exist injected on the same side of the tail)—especially when testing large numbers of animals, unless at that place is some physical aberration at the injection site.

Stride 4: Reading the Test—

The test must be read between 66 and 78 hours afterward injection (72 hours is optimum). The veterinary who made the injection must be the veterinarian who reads the test result. Exceptions must be approved in writing by the USDA, Veterinary Services, Assistant District Managing director. The veterinarian must determine the results of the test by both observation and palpation of the injection site.
Verify the identification of the restrained animal and raise the tail to exert slight tension on the caudal fold.
Visually audit the injection site closely and palpate information technology carefully to detect changes from the normal. Any swelling, sensitivity, or increase in thickness of the skin is considered to be a positive response to the tuberculin. The size of responses may vary and are non indicative of infectious status. Responses may exist minor, difficult, pea-sized responses, diffuse responses, confining responses, or large responses. If there is dubiousness about whether a response has occurred, palpate the reverse side of the tail to decide if there is a change from normal. Any observed change should be recorded.
Test ascertainment without palpation is unacceptable.

Step five: Recording the Results of the Test—

Apply VS Course half dozen–22.
Enter "N" (negative) when yous detect no alter in the tissue at the site of injection.
Enter "South" (doubtable) when you observe or palpate any increase in caudal fold thickness, size, or sensitivity, at the injection site as described above.

Reactions and Interpreting Test Results

If an animal is exposed to the antigens present in bovine TB, a tuberculin injection results in a delayed hypersensitivity reaction manifested by swelling and induration at the injection site. A positive response usually begins inside eight to 12 hours and peaks virtually 72 hours later injection.

If the test produces any type of response, immediately notify your APHIS –VS District Function and Land animal wellness officials. The caudal-fold test is used as a presumptive diagnostic procedure, and animals classified as suspect must be evaluated further past the comparative cervical (CC) test, gamma interferon test, or sent straight to slaughter nether permit.

Only Federal or State regulatory veterinarians who have had specialized preparation may conduct the follow upward testing. Follow-upwardly CCT testing must be performed inside 10 days of the initial caudal-fold injection in cattle and bison, or the herd owner must await 60 days (xc days for cervidae) after the injection of the CFT before a follow-up CCT tin be administered. If the gamma interferon examination is used as a follow upward examination the blood must be drawn within 30 days of the CFT inject date. Annotation: The gamma interferon examination is not canonical for use in Bison or captive cervidae. If the CCT or gamma interferon exam indicates that the animal is a reactor, all further herd testing is conducted by Federal or State regulatory veterinarians.

Accredited veterinarians and regulatory veterinarians are expected to meet the caudal fold response rates as identified in the 2005 Bovine TB Eradication Uniform Methods and Rules, Appendix C. Improper injection or ascertainment techniques, mishandling of tuberculin, and other events may atomic number 82 to inaccuracies in the examination and true disease status may exist missed. See the Bovine TB Eradication Compatible Methods and Rules for more information. The most current version of this VS-published document is posted at:

http://www.aphis.usda.gov/animal_health/animal_diseases/tuberculosis/downloads/tb-umr.pdf

nine CFR part 77.1 Material incorporated by reference.

Uniform Methods and Rules—Bovine Tuberculosis Eradication. The Uniform Methods and Rules—Bovine Tuberculosis Eradication (Jan 22, 1999, edition) has been approved for incorporation by reference into the Code of Federal Regulations by the Director of the Federal Register in accordance with v U.Southward.C. 552(a) and 1 CFR part 51.

(a) The procedures specified in the Uniform Methods and Rules—Bovine Tuberculosis Eradication (January 22, 1999, edition) must be followed for the interstate move of sure animals regulated under this part.