Infectious bovine rhinotracheitis (IBR) is a fast-moving upper respiratory disease that can quietly drain profitability in beef and dairy herds. Caused by bovine herpesvirus 1 (BoHV-1), it spreads quickly through close contact and, like other herpes viruses, it doesn’t leave the herd once it arrives. The highly infectious nature of the virus makes control challenging during an outbreak, and the typical herpesvirus facet of latency has made eradication extremely difficult in most countries. This guide keeps things simple and explains what IBR looks like, how it spreads and what you can do to protect cattle and performance.
Why this disease matters
IBR contributes to respiratory disease, milk losses, abortions and secondary pneumonia. Once established, it can persist for years because recovered cattle carry the virus and can shed it again under stress.
“The highly infectious nature of the virus makes control in the face of an outbreak challenging,” says Dr. Oliver Maxwell.
How IBR spreads
IBR moves via respiratory droplets, nose-to-nose contact, shared facilities or equipment, and wind-assisted spread. Latently infected cattle may shed virus without looking sick, which is why outbreaks recur even without new introductions.
Latency and reactivation
After the first infection, BoHV-1 settles in nerve ganglia. Stress events – such as transport, regrouping, calving, weather swings, etc. – can wake the virus and restart shedding in animals that appear healthy.
“This latency may then be reactivated by stress events or immunosuppression; indeed, recrudescence has been demonstrated with administration of dexamethasone 10 weeks postinfection,” Maxwell says.
What an IBR outbreak looks like
Typical signs include high fever (greater than 40°C), dullness, being off feed, harsh breathing, cough, watery nasal discharge that becomes thick and puslike, and eye discharge. White plaques may be visible on the nasal mucosa or tongue. In many housed groups, 80%-100% of animals show signs; mortality is usually low, but losses rise sharply when secondary pneumonia strikes.
Secondary bacterial involvement
IBR damages the airway lining and weakens local immunity, opening the door for bacterial pneumonia – especially with Mannheimia haemolytica.
“In the case of secondary pneumonic infection with M. haemolytica, mortality rates can increase significantly,” Maxwell says.
What the virus does inside the animal
BoHV-1 replicates in the nasal and tracheal mucosa, causing swelling, ulceration and sloughing. Tracheal walls can become markedly thickened, producing coarse rales. Sloughed tissue and fibrin create debris that promotes bacterial invasion.
Characteristic lesions
During acute disease, the trachea and nasopharynx show intense ulceration and necrosis with fibrin deposition. These changes explain the harsh sounds on auscultation and the heavy discharge seen in clinical cases.
“The wall swells to 2 centimetres thick, causing severe stenosis of the trachea and producing the characteristic rales on auscultation,” Maxwell says.
How common is IBR?
IBR is prevalent in most cattle-producing regions worldwide. Only a handful of European countries have official IBR-free status. Without structured control, herd exposure and performance losses tend to rise over time.
Diagnosing IBR
Vets may diagnose based on signs, but lab confirmation is important. Fluorescent antibody tests and polymerase chain reaction (PCR) tests can be run on swabs; paired serology helps during outbreaks. Postmortem often shows a red, thickened tracheal mucosa covered in mucopurulent exudate.
DIVA-friendly vaccination
Modern marker vaccines delete the glycoprotein E (gE) antigen so testing can distinguish vaccinated animals from naturally infected ones – critical for monitoring and control.
“Marker vaccines have the glycoprotein E antigen deleted, allowing for a DIVA test to confirm ‘wild type’ versus vaccinated status,” Maxwell says.
Vaccination: Your best defence
Use gE-deleted marker vaccines for herd programs. Some newer vaccines also delete the thymidine kinase (TK) gene to increase safety and further reduce virulence. To maintain protection, vaccinate the whole herd every six months and keep consistent records.
Why six-month boosters?
Immunity wanes by six months, so countries that have reduced IBR rely on whole-herd vaccination at six-month intervals with monitoring.
“Hyperimmunization has proven to be effective to control and eradicate IBR,” Maxwell says.
Practical steps that help on the farm
Improve ventilation, avoid overcrowding, keep groups stable and reduce stress during handling and transport. Isolate and test new arrivals, separate sick animals early, and clean equipment between groups. Work with your veterinarian on a herd plan that aligns vaccination, testing, introductions and outbreak response.
Bottom line
IBR is persistent, contagious and costly, but it is manageable. With marker vaccination, six-month boosters and straightforward biosecurity, you can turn IBR from a constant headache into a controllable risk. Healthy cattle breathe better, breed better and perform better – and that pays.
Adapted from a paper, with direct quotes, by Dr. Oliver Maxwell BVSc BSc (Hons) MVM DipECBHM MRCVS.
This is the second article in the Detect and Protect technical series from HIPRA Canada, dedicated to advancing cattle health. We explore the causes, diagnosis and prevention of bovine respiratory disease (BRD) to empower producers with science-based insights and solutions.
