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Most dairy cattle due for TB test before entering Texas

On March 18, Texas joined more than 33 other states that require most dairy cows and dairy bulls to have a negative test for cattle tuberculosis (TB) within 60 days before entering the state.

Young dairy heifers and bull calves hauled to Texas will have to be officially identified with an ear tag and will be restricted at a designated facility until they test negative for TB at six months of age. With 807 registered dairies, Texas ranks among the top 10 states in the nation for dairy cattle and milk production. Nearly 62,000 dairy replacement animals entered the state in 2004.

The new regulation provides testing exemptions for dairy cattle that originate from herds tested yearly under a TB-accreditation program, neutered dairy cattle being fed for slaughter, and dairy cattle delivered directly to slaughter. These animals, however, must have a certificate of veterinary inspection, issued within 30 days prior to movement.

“During the past 18 months, the 335,000 cattle in Texas dairies have been tested for cattle TB, and it is only prudent to ensure that incoming replacement dairy cattle also are free of the disease,” said Dee Ellis, who heads up the Animal Health Programs for the Texas Animal Health Commission, the state’s livestock and poultry health regulatory agency. Beef cattle will continue to enter Texas under existing regulations.

Ellis pointed out that concerns about cattle TB in dairy operations have increased, particularly after four dairies and two related operations were found to be infected during the 2004 federal fiscal year, from October 2003 through September 2004. Two infected herds and a dairy heifer-raising facility were found in New Mexico, as well as a dairy heifer-raising facility in Arizona, states which had the U.S. Department of Agriculture’s TB-free designation. An infected dairy was found in Michigan. During Texas’ statewide dairy testing, an infected herd was found in Hamilton County, and subsequently depopulated.

Ellis explained that infected cattle can expose herd mates to the TB bacteria by coughing or contaminating feed with drool or nasal discharge. In confined operations, like dairies, TB can spread more readily. Because dairy animals often are kept for several years, infected animals can develop the characteristic internal lesions in the lungs, lymph nodes and other organs, and begin the cycle of disease exposure again. Infected cattle may pose a risk to handlers who work with the animals daily. Milk from commercial dairies is heat-treated, or pasteurized, to kill bacteria. At slaughter, state or federal meat inspectors examine carcasses, collect tissue samples for testing, and condemn meat unsafe or unfit for human consumption.

“Because there is no effective treatment for cattle TB in livestock, an infected herd either must be destroyed under a government indemnity, or payment, or placed under quarantine and tested repeatedly over a period of months, until all animals that respond to a test are depopulated. After being released from quarantine, the herd still is subjected to a yearly test for five years to ensure the animals remain free of the disease. Often, the best option is depopulation, as this eliminates the potential for the disease to reoccur or spread,” Ellis said.

After two TB-infected cattle herds were detected in 2001, Texas lost its USDA TB-free designation just a few months shy of its two-year anniversary for achieving the coveted status. New Mexico and California also have lost TB-free status, and Michigan last summer gained split-state status, while it continues to deal with TB in cattle and free-ranging deer in the state’s Upper Peninsula.

Ellis said the plan to regain Texas’ TB-free status was developed with the dairy and beef cattle industry, and one aspect involves testing all dairies, a chore already accomplished on at least 2,400 purebred or seed stock beef cattle herds.

More than 500 beef cattle herds have been tested in Texas, with no TB infection detected, but more herd tests are needed to provide adequate disease surveillance. The USDA has extended funding to pay for herd tests, and more than 500 private veterinary practitioners in Texas are certified to provide the service.

To learn more about the TB testing program, call the TAHC at 1-800-550-8242, the nearest TAHC area office, or a private veterinary practitioner.

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