Tuberculosis found in South Dakota cattle herd
Bovine tuberculosis (TB) has been confirmed in a South Dakota beef herd for the first time since 2017. State veterinarian Dr. Dustin Oedekoven says that an infected cow was initially identified in January by meat inspectors during routine inspection at a Minnesota packing plant. Records linked the cow to a Corson County beef herd which had additional animals confirmed as infected by recent laboratory testing.
“The index cow (the initial cow identified with lesions at slaughter) did not have official ID or a backtag,” Oedekoven said. “The lot she was in had been sourced from two different auction markets in different states with multiple sellers. It took some time to narrow the possibilities to find the herd she most likely originated from. State animal health officials conducted TB skin testing in the herd, and some cattle that tested positive were necropsied at the Animal Disease Research and Diagnostic Lab in Brookings. Samples were collected and tested positive at the National Veterinary Services Lab in Ames, Iowa.”
The state veterinarian’s office is working closely with the affected herd owner, as well as other producers in the area, USDA officials, Standing Rock Sioux Tribal officials, area veterinarians and wildlife officials to evaluate the extent of the disease and mitigate further spread.
“State and federal officials are now tracing animals that had been sold out of that herd, or that had been brought into the herd, as well as conducting testing in neighboring herds. As calving has begun in some of the herds of interest, testing may be delayed until late spring or summer,” Oedekoven said.
The state vet’s office will keep producers updated as the case proceeds, but Oedekoven says, “It’s a slow process by nature.”
The last case of TB discovered in South Dakota was in 2017 in Tripp County. That case was announced in November. The case before that was in Harding County in March of 2017. Oedekoven said TB cases in South Dakota have been identified in November, January and February. “These have all been cows that were culled from a spring-calving beef herd, sold through a South Dakota auction market, and then either slaughtered right away, or fed for a short time prior to slaughter. Slaughter surveillance has been the reason each cow was identified, leading back to finding additional infected animals in the herd. I think the timing is mostly coincidental with traditional timing of selling cull cows, and those cows subsequently being subject to inspection – our surveillance system works.”
Oedekoven said bovine TB is not currently a threat to food safety in the United States, thanks to milk pasteurization and comprehensive meat inspection programs.
Bovine tuberculosis is a chronic, slowly progressive respiratory disease of cattle. Infected animals may transmit infection to other animals when in close proximity for prolonged periods. Cattle rarely exhibit visible signs of illness and testing of cattle herds is necessary to determine if animals are infected. The US has nearly eliminated bovine TB due to a cooperative eradication campaign. South Dakota has officially been recognized as free of the disease since 1982.
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Outtagrass Cattle Co. cartoon by Jan Swan Wood for the June 19, 2021, edition of Tri-State Livestock News