An unprecedented number of cattle herds in South Dakota and North Dakota died due to anthrax during the summer of 2005. South Dakota State University Extension Veterinarian Russ Daly recommends vaccinating herds before turning cows and bulls out to summer pastures.
Climatic and pasture conditions such as hot, humid weather, excessive pasture flooding, and excessive drought are all conditions associated with anthrax outbreaks in the past. Such conditions are favorable for the exposure of grazing animals to anthrax spores, which may remain viable in the soil for many years.
"Fortunately, anthrax is a disease for which there is an effective vaccine that may be used to help decrease death losses," Daly says.
For maximum immunity, cows and calves should ideally be vaccinated at least four weeks prior to the time the disease usually appears, although protective immunity will usually develop in eight to ten days. Immunity from vaccination is considered to last for at least six months and possibly up to one year.
In last year's anthrax outbreak in South Dakota, the first cases were noted in mid- to late July. Numbers of cases were highest in late July and early August, and remained steady through most of the month of August. Considering these factors, vaccinating cattle going to summer pasture beginning now should be an optimal time to maximize protection from anthrax throughout the grazing season.
"Over the years, many thousands of doses of anthrax vaccine have been used in South Dakota cattle herds. It has been a safe, effective, and relatively inexpensive product. Producers should contact their veterinarian for advice on administering the vaccine," Daly says.
Producers suspecting cases of anthrax on their pastures should immediately contact their veterinarian for proper diagnosis and advice.
For more information about anthrax, click HERE.