IBR stands for Infectious Bovine Rhinotracheitis. As the name suggests it is an infectious respiratory disease of cattle.
What causes IBR?
IBR is caused by a virus called Bovine Herpes Virus-1(BHV-1). BHV-1 is unique in that after cattle become infected they become carriers of the disease. The virus can lie latent – or hidden in the animal’s body. It is not possible to tell from looking at the animal if they are a carrier. You need to do a blood test to establish if the animal is a carrier. The disease can reactivate at times of stress. When it reactivates the animal sheds the virus which can result in other animals becoming infected.
What are the signs of IBR?
The clinical signs associated with the disease are fever and respiratory signs such as runny nose, discharge from the eyes and coughing. IBR in dairy herds is associated with a drop in milk yield. It can also cause abortion.
How is IBR spread?
Direct nose to nose contact is the main cause of spreading within herds. It can also be spread via mucus or via aerosol, in the air breathed or sneezed out. Airborne spread can occur over distances of up to 5 meters. IBR can be transferred by objects, things and people and can also be spread by semen from infected bulls.
When latently infected or carrier animals become stressed they shed enough virus to infect naïve (uninfected) animals. These newly infected animals shed much larger quantities of virus and spread it to other naïve animals. It is this spread from recently infected to naïve animal that is responsible for the main spread of virus in an outbreak and spread of disease throughout a naïve herd. The latently infected animals really just act as a reservoir for virus. A newly infected animal can infect up to 6 to 7 naïve in-contact animals, so you can see how easily the virus can spread though the herd when the animals are in close contact.
How can you diagnose IBR?
If your herd is experiencing some of the clinical signs described above and you suspect IBR is causing a problem in your herd talk to your vet. Nasal swabs can be used to identify cattle that are shedding virus and bloods can be used to identify latently infected animals.
How can I treat IBR?
Once animals are latently infected or carriers they remain carriers for life. You can treat the animals individually as they show clinical signs but to control the disease and its impact on herd production you need to vaccinate.
Which vaccine should I use – live or inactivated?
There are two types of IBR vaccines, live vaccines and inactivated vaccines. Vaccinating with the live vaccine results in less shedding of BHV-1 (IBR) virus in newly infected naïve animals than the inactivated vaccine ˡ. There is also limited evidence that using inactivated vaccine can result in a better reduction of shedding by reactivated latently infected animals than live vaccine³. However, a number of studies have showed that live IBR marker vaccines provide better protection against clinical signs than inactivated vaccinesˡ ². Speak to your vet for more information on the advantages of live IBR marker vaccines and which vaccination regime is most suited to your herd circumstances.
(1) An attenuated bovine herpesvirus 1 vaccine induces better protection than two inactivated marker vaccines, Bosch et al, Veterinary Microbiology 52 (1996) 223-234
(2) H. Kuijk TIERÄRZTLICHE UMSCHAU (2004) 59, 3, p 168 – 172
(3) Bosch, J. C., Kaashoek, M. J., & Van Oirschot, J. T. (1997). Inactivated bovine herpesvirus 1 marker vaccines are more efficacious in reducing virus excretion after reactivation than a live marker vaccine. Vaccine, 15(14), 1512-1517.