Anthrax, bovine - USA (TX)

International Society for Infectious Diseases
<http://www.isid.org>


On Mon, 18 Sep, The Texas Department of Health Services alerted its
veterinary public health officers that  the Texas Veterinary Medical
Diagnostic Laboratory (TVMDL) had confirmed a diagnosis of anthrax in
a 4-year-old Charolais cow in Kinney County.

I checked with the veterinarian in Bracketville, Dr. Zach Davis, who
confirmed that he had been called out to a farm 6-7 miles SW of the
town with this dead cow about 10 days earlier. A Charolais bull had
died of anthrax on the same farm and in the same pasture in early
June 2006. After the bull died the owner's herd of 35 head had been
vaccinated, including this cow, which later died. Other than the
possibility of a misvaccination in the confusion of running animals
through the chute, neither of us could come up with an explanation
other than a duff batch of vaccine. The owner had bought the vaccine
at a local feed store. The herd was revaccinated after the 2nd death.

The 1st death had occurred during the hot dry weather. It had rained
since. The cause for the 2nd cow was posited that the salt block for
the herd was down to pieces and that salt from it had run into the
soil, which the cattle had been noted to be licking and abrading. The
graze was minimal. So logically this field had had an anthrax case
buried in it some time in the past. The last case of anthrax that
Zach had seen in the area was 15 years ago, a horse, some 3 miles
from this affected farm.

Because of the epidemic in 2001 in this area, the ranchers have got
into the habit of feeding chlortetracyclene in their feed at levels
anywhere from 300 to 3000 gms per ton; anything over 50 gms needs a
veterinary prescription. Thus any diagnosis of anthrax in this area
should take this into account, and as a matter of routine, check for
antibiotic resistance in the confirmatory culture. This Kinney County
farm was not feeding antibiotics to its cattle.