Texas vets Bangs vaccinate adult cattle leaving state

News
Oct 29, 2011
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Due to severe drought, thousands of Texas cattle are being moved to other states. Texas Animal Health Commission (TAHC) records from Certificates of Veterinary Inspections indicate that 24,330 breeding cows left Texas in August 2011 compared to 3,815 breeding cows leaving the state in August 2010. Those cows were sharing the road with 151,325, versus 64,837, non-breeding cattle (feeders) during those two respective months in 2011 and 2010. And they still continue to leave the parched Lone Star State. Within that sixfold difference in breeding cows leaving desiccated pastures, it has been estimated that at least a third of those cows leaving Texas so far have been shipped to western states where grazing and hay are plentiful. A large portion of those shipped cattle originate from some of the bigger ranches in northwest and West Texas.

Some western states require brucellosis (Bangs) vaccination of female cattle prior to entry. Texas, a Brucellosis Free State, does not require cattle producers or owners in the state to calfhood vaccinate their age eligible (4 to 12 months) heifer calves against brucellosis. However, calfhood immunization is common and strongly urged by large animal veterinary practitioners, TAHC, USDA and many state and national cattle organizations.

This past August, in order to assist producers in meeting those states’ entry requirements, TAHC provided a protocol for Texas licensed accredited veterinarians to use when administering brucel losis vaccination in beef and dairy cattle over the age of 12 months. Prior to this, only government officials could administer brucellosis vaccine to adult cattle in Texas in those situations when receiving states required brucellosis vaccination of all female cattle entering, yet calfhood vaccination has not been performed.

Vaccination of sexually immature female cattle against Brucella abortus, also known as Bangs disease, began more than a half century ago in an effort to prevent the transmission and spread of bovine brucellosis which can cause abortion in cattle, weak calves and low milk production. Brucellosis can additionally cause fertility problems in bulls. This bacteria is also important with respect to public health concerns as it can be transmitted to people and is the causative agent of undulant fever in humans.

Strain 19, the original brucellosis vaccine administered by federally accredited veterinary practitioners and government officials, did not come without some problems. The primary issues with calfhood vaccination using the reduced dose of strain 19 were interference by that vaccine with brucellosis testing, oftentimes resulting in false positive tests.

The maximum age for calfhood vaccination was lowered from 12 months to 10 months to reduce the number of possible abortions and false positives.

Other problems were encountered when accidental inoculation into a person of the modified live strain 1 vaccine occurred, thereby exposing them to a reduced and altered dose of brucellosis bacteria. This exposure was usually via needles containing strain 19 vaccine, although splashing of vaccine into the mouth, eyes and other mucous membranes was another possible entry for contact.

The first new brucellosis vaccine in 50 years, strain RB-51 was approved by Animal and Plant Health Inspection Service in February 1996 and became available to all federally accredited licensed veterinarians.

RB-51’s biggest advantage over strain 19 vaccine is its ability to protect against bovine brucellosis but not interfere with diagnostic testing for the disease. This allowed the maximum age for calfhood vaccination to be changed from 10 months back to the original 12 months. The problems associated with accidental exposure of humans to brucellosis vaccine, such as fever and malaise, have been vastly minimized with the RB-51 vaccine. Strain 19 is no longer used in private practice.

Prior to August 2011, accredited Texas licensed veterinarians were able to administer brucellosis vaccinations in the state only to heifer calves that met the age requirements. Historically, adult brucellosis vaccination has been the responsibility of state or federal veterinarians under unique situations or certain circumstances such as those encountered by government agencies working with affected herds within Texas.

Now, Texas licensed veterinarians qualifying under federal accreditation guidelines may vaccinate adult cattle against brucellosis in the state.

Brucellosis vaccination and/or testing of test eligible cattle is required by some states for entry unless cattle are going straight to feedlots, slaughter or originating from a Certified Brucellosis Free Herd. There may be other exemptions, depending upon the state. Age requirements for cattle and length of testing interval between testing, vaccination and transport may vary between states. In addition to brucellosis testing, some states require all female cattle to be brucellosis vaccinated. Consequently, making adult brucellosis vaccination more readily available in Texas affords increased opportunities for movement of cattle in situations where females have not been previously calfhood vaccinated.

Official Texas adult brucellosis vaccinates with RB- 51 must be more than 12 months of age and be brucellosis tested at the time of vaccination or within 10 days prior to receiving the vaccine. States vary as to the amount of vaccine required to be given; for example, Wyoming and Montana require a 2 cc dose (full calfhood dose) of RB-51 for import of non-calfhood vaccinated female cattle. Texas requires a 1 cc dose of RB-51 vaccine for adult vaccination of cattle within their state, although the full 2 cc dose may be used following consultation with TAHC.

All adult vaccinates in Texas must be identified in the right ear with official USDA silver brucellosis test ear tags, not the orange calfhood vaccinate tags, or with official electronic ear tags approved by TAHC. They must also receive the official brucellosis tattoo specific for adult vaccination.

When used in pregnant cows, the RB-51 brucellosis vaccine has resulted in abortion in a few rare documented cases. Nonetheless, this issue should be discussed by veterinarians with their clients prior to vaccination to determine the cost/benefit of adult vaccination. The RB- 51 vaccination has a 21-day withdrawal period.

TAHC officials report that 19,753 heifers and 1,155 cows have been adult vaccinated with the RB-51 vaccine in Texas since Jan. 1, 2011. That figure is no doubt lower than actual numbers vaccinated as, currently, many vaccination charts are still being processed. It is always necessary to check interstate requirements of individual states before transporting livestock. Locating pasture and shipping all or part of one’s cow herd is an ordeal in and of itself. However, TAHC has eased some of the mental loads of producers by helping their shipped bovine loads meet the entry requirements of their new ‘home away from home.’ — Ginger Elliot, WLJ Correspondent

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