Jessica Laurin, DVM, Animal Health Center of Marion Co., Inc., Marion, Kan., has many stocker/backgrounder clients in her area on the edge of the Kansas Flint Hills. Speaking at the 2011 Annual Western Veterinary Conference, Laurin says, “Stocker/backgrounders in my area will purchase calves between 350-650 pounds to sell between 800-950 pounds, depending upon the market. Each year brings a new set of expectations and challenges.” Because of that, Laurin uses a variety of diagnostic tools and approaches for working with stocker/backgrounder clients.
“We utilize ear-notching for BVD at processing on arrival for purchased cattle,” Laurin says. “My producers and I discuss and choose cattle to test based on size, origin, and whether cattle are purchased at the sale barn as singles, less than five head per farm, or over five head per farm, and quality or price.” The first test offered is immunohistochemistry (IHC), where ear-notches are placed in formalin, stained, and read. IHC is a highly accurate gold standard test, and has a two day turnaround. Another test is the ELISA which has high accuracy, but a higher chance of false positives vs. IHC, but very quick turnaround time. “The cost of the ELISA test depends upon the supplier to the diagnostic lab, so this test is shopped around for cost as well as turnaround time,” Laurin explains.
The newest offering is real-time PCR which offers high accuracy, a higher chance of false positives vs. IHC, and fairly quick turnaround time. There are also labs that offer pooled PCR in groups of up to 50 ear-notches per pool, and then a positive pool is broken down and tested individually. Producer concerns are that it is labor intense, if lab reports are reported quick enough to be effective, and the logistics to make turnaround time practical. “This test can also be utilized in face of an outbreak if not run at the time of initial processing,” Laurin says. “Some order buyers offer to ear-notch test before the cattle are shipped. A BVD-positive test should be confirmed in two weeks with a repeated test to verify the animal is PI vs. TI (transient infection).”
It is important that on every respiratory case that organs other than the respiratory system are also examined. Laurin says to examine the abomasum, liver, kidneys, small intestines, cecum, mesenteric lymph nodes, if not more. “With respiratory deads, I check for abomasal ulcers, parasitic nodules, infection involving the intestines and mesenteric lymph nodes, and open the cecum to check for coccidiosis,” she says.