Diagnostic Insights for Veterinary Nurses
August 2019

Calving Season and Respiratory Disease

By Kelli Millsap, RVT

Calving season will soon be upon us and with that always seems to come calves getting sick for one reason or another. Two of the most common diseases cow-calf herds experience are respiratory disease and neonatal diarrhea.

In beef calves of preweaning age (three weeks or older), respiratory disease has been reported to be the leading cause of death on cow-calf operations in the United States1. Bovine respiratory disease is associated with both viral and bacterial pathogens. The most common viral agents are bovine herpesvirus type 1 (IBR), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), and possibly bovine respiratory coronavirus. Additionally, there are four primary bacterial agents that are commonly found; Mannheimia haemolytica, Pasturella multocida, Histophilus somni, and Mycoplasma bovis.

The Kansas State Veterinary Diagnostic Laboratory offers a PCR test targeting these organisms. The test can be completed on a single deep pharyngeal swab. To collect the appropriate sample, a sterile, double-guarded equine culture swab and either a red top tube containing 0.25 mL of sterile saline or Aimes viral transport media or Copan E-swab™ tube are needed. Gel media is never appropriate for PCR as it interferes with the test reaction.

To collect the sample, insert the guarded culture swab into the medial aspect of the nares until it reaches the half-way point between the lateral canthus of the eye and the external nares. (For smaller calves, resistance may be felt before reaching the half-way point. If resistance is noted, do not attempt to advance the culture device any further.) Once the target location is reached, advance the inner guard far enough to pop thru the end of the outer guard. Now advance the swab as far as possible and using and in-and-out movement (8-10 times is sufficient) collect the sample. Pull the swab back inside the guard before removing from the nares to prevent contamination. Place the swab into your transport media and cut the swab to fit the length of the tube.

Watch a short video on how to collect a deep pharyngeal swab.


  1. A. Woolums; Risk factors for BRD on cow-calf operations; THE AABP PROCEEDINGS—VOL. 48; SEPTEMBER 2015

Kelli Millsap is Registered Veterinary Nurse in the Veterinary Health Center at Kansas State University.

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