Infectious Bovine Rhinotracheitis – IBR – is a herpes virus that can cause respiratory disease in cattle of all ages or reproductive disease in breeding females. It is caused by Bovine Herpes Virus 1 – BHV 1 – and has a worldwide distribution. Initially the virus was recognised as causing severe upper respiratory tract disease in cattle – classically these would have presented with a severe mucopurulent discharge from the nose and eyes – lots of thick pus! The animals had a very high temperature and they would have shown coughing, increased breathing and generally off colour and inappetant. The disease would have spread rapidly on a farm and mortality could be very high.
Today we tend to see a more subtle disease pattern. There can be a background cough with slight nasal and ocular discharge. We then start to see the more subtle signs of an effect on production – lower milk yield and reduced fertility. These production effects can be missed and represent a “drag” on farm performance.
IBR is spread by carrier animals. Any animal that becomes infected will become a latent carrier – as humans do with the herpes simplex virus that causes cold sores. These latently infected animals have no clinical signs but can start to re-excrete at any time following a period of stress or an immune challenge. These latently infected animals are the source of infection in the herd. For an IBR free herd these animals are the greatest danger.
IBR can be controlled and avoided. The first step is to establish your IBR status with your vet – this can be done via blood samples or a bulk tank sample. We look for antibodies proving exposure to IBR virus. If antibodies are present, and there are no vaccinated animals present, then the animals have been exposed to IBR and will have latent carriers present.
If you are fortunate enough to be IBR negative, then you must take steps to protect that status – negative also means the herd is susceptible to infection. Biosecurity is key here. As discussed above the biggest risk to your herd is from purchasing latent carriers – unless you sample incoming animals you won’t know their health status. You should do a biosecurity risk assessment with your vet as part of your herd health control. This will include assessing risks from neighbouring cattle, farm visitors etc. You may choose vaccination as one control option if your risk assessment of infection is high.
Or you can choose to buy from an IBR Accredited herd. There are CHeCS accreditation schemes for the common infectious diseases of cattle. Cattle herds can accredited free from IBR, BVD, Leptospirosis, Johnes, Neospora and TB. The schemes for each disease run separately so you can choose what suits you.
If you are IBR positive, then your aim is to limit the effects of the infection in the herd – reduce the clinical signs – and to prevent the development of latent carriers. You can choose to sample all the individuals in the herd and to cull the positive animals. This can be expensive and may not be economically viable.
Vaccination will limit disease transmission between animals, helping to protect uninfected animals. It will also prevent the development of latency thus slowing spread within a herd. Carried out correctly, vaccination should also reduce the intensity and duration of clinical signs.
Using a live marker vaccine means surveillance testing can continue to be carried out after vaccination, as vaccinated animals can be distinguished apart from animals exposed to wild type IBR.
Every cattle farm – dairy or beef – should know their IBR status as the effects of the disease can be subtle and production limiting. The principles of infectious disease control then apply…
- Know your health status for the important diseases
- Assess your biosecurity to keep disease out and to limit disease spread.
- Implement prevention and /or control measures
- Work with your vet on call the above