Screen Incoming Livestock

Take care when adding to your herd this summer.

Published on: Aug 1, 2006

There is a lot of good cattle coming onto the market this summer due to the drought, but you still have to be concerned about their health and the risk that that may infect your existing herd, says Rus Daly, SDSU Extension Veterinarian Russ Daly.

"Especially important during the summer months are diseases that affect the reproductive health of the herd," he says.

Bovine viral diarrhea, infectious bovine rhinotracheitis (IBR or "red nose"), trichomoniasis, and leptospirosis are among the most serious diseases. They may result in infertility or pregnancy loss in cow herds. Other non-reproductive diseases are also important considerations, such as Johne's disease.

"In addition, common viruses and bacteria that cattle are exposed to on a widespread basis, such as pinkeye and some respiratory viruses and bacteria, can cause problems in a new herd when cattle are exposed to different strains of those disease-causing agents. These agents can be transmitted from clinically healthy animals that have good immunity against those particular strains. In these cases, clinical disease results when the new animals' immune system does not recognize and deal with these novel versions of the germs," he says.

When purchasing animals, Daly recommends you follow at least these four steps:

  • Learn as much as possible about the health status of the purchased animals. What health monitoring or vaccination programs have been used?
  • Isolate purchased animals from your existing herd for 30 to 60 days. For diseases that are not characterized by persistent or long-term shedding from the animal, this gives newly purchased animals a chance to recover from the condition and not spread it to the existing animals.
  • Ear-notch test both cows and calves for BVD persistent infection (PI) before new animals enter the herd. This condition is simple to test for. Because BVD PI animals shed virus for life, any length of isolation period is not sufficient to prevent transmission to other animals. Introduction of BVD to cows during early pregnancy can result in a devastating occurrence of infertility, pregnancy loss, and eventual birth of more persistently infected calves. This can happen even despite the existing herd having been vaccinated against BVD infection.
  • Consider tests for other diseases such as Johne's or leptospirosis while animals are in isolation. 

"Work with your veterinarian to design a practical plan for dealing with incoming animals," Daly recommends. "Taking careful steps before mixing new animals into the herd will greatly decrease the threat of losses due to introduction of diseases."