Bovine Respiratory Disease

By Dr Erica Kennedy, District Veterinarian, April 2020

In the last couple of weeks, we have seen cases of pneumonia killing cattle in the Central West. With producers keen and starting to restock we hope that some tips may help to avoid the heartache of expensive cattle succumbing to Bovine Respiratory Disease.

About the disease

Bovine Respiratory Disease is the most common cause of disease in feedlot cattle, you might already be thinking it does not apply to your situation but think again. Many of the same risk factors apply when restocking, especially when using those cattle to strategically graze paddocks in a more intensive situation. We see this disease most frequently in Autumn and Early Winter. Bos Taurus (British Breeds) are more susceptible than Bos Indicus (Brahman/Santa Gertrudis type) cattle. Production losses are felt not only in deaths of severely affected livestock but in reduced average daily gains. One Australian study of 2468 feedlot cattle with an average induction weight of 340kg showed that the ADG of cattle affected with BRD was on average, 700g lower per day than that of unaffected cattle.

BRD is a what we call a ‘disease complex’ rather than one bug that causes disease. For BRD to occur there generally needs to be three things: Stress + Virus + Bacteria. The bacteria that are involved live in cattle’s throats, some may have more than others, but the long and short of it is that you can’t stop all the bacteria from being around. The viruses are also carried by the cattle, the most common one of these (IBR) is a herpesvirus (different to the one affecting humans) that lives in the throat of some cattle, just like the bacteria do. There are also a handful of other viruses (including Pestivirus) that have been linked to BRD. The one BIG factor in BRD development that we can have some control over is STRESS.

Stress factors and mitigation measures

The most common stressors (and ways to mitigate) are listed below:

  • Weaning – low stress, avoid buying recently weaned cattle where possible
  • Saleyards – the extra transport/yarding increases stress and exposure to viruses
  • Transport – reduce the distance were possible, acknowledge the impact long distance travel will have on your BRD risk
  • Time off feed – proportional to stress, feed hay as soon as they come off the truck to fill them back up
  • Co-mingling/New Social groups – one of the biggest factors. Not only are cattle exposed to viruses they’ve never encountered before, don’t underestimate the impact that a change in social group has on stress. Re-establishment of the ‘pecking order’ is a major stress.
  • Handling/yarding – do the minimum required, minimise time in yards, if you do not know the previous handling conditions of the cattle, keep it as quiet and low stress as possible, ie. Don’t use dogs in yards as those cattle may have never seen a dog before!
  • Weather – big fluctuations in temperature (rather than minimum temperatures – except for maybe in the dead of winter) will increase the amount of BRD. If bringing cattle down from Northern Australia this may have an impact too.
  • Water changes – switching from bore to rain or particularly from rain to bore can have a big impact on water intake. Keep this in mind and ask questions where possible about water source the cattle are used to. Not easy to change but will increase your likelihood of BRD.

The process of cattle succumbing to BRD is outlined in the diagram below:

The lungs are a perfect home for these bacteria and they replicate very quickly and cause a huge amount of damage – pus, inflammation, scar tissue, reduced amount of oxygen in the blood. This process causes a high fever, depression, reduced feed intake and respiratory signs. If you’ve ever had pneumonia or a bad chest infection you’ll know that you feel really flat, don’t want to eat, you’ve got a runny nose and feel like you want to cough phlegm up all the time. The cattle are exactly the same, initially you’ll see just a bit of a watery nasal discharge and maybe a soft, tentative cough. As the infection gets worse you’ll hear a loud, harsh cough and sometimes see a cloudy nasal discharge. At this stage you will notice they are dull, will stand on their own, are taking really short and shallow breaths and may have their neck outstretched.

To see any of these signs though you need to spend 5 or 10 minutes a day watching them, signs can be subtle and it’s really important to pick any issues up early as the disease can progress rapidly in a couple of days. If you see any signs you’re concerned about, please contact your local vet. Treatment of BRD involves anti-inflammatories to help reduce the fever and antibiotics that are targeted to killing the specific bacteria that are causing the problem. Please DO NOT use some old penicillin that you’ve had in the fridge for years, it’s not the right antibiotic to use and will only prolong the course of disease.

Vaccination options

The good news is that there are some vaccines that can be used to help prevent BRD! They are not a silver bullet (you still need to try and reduce those stressors as much as possible) but are a great tool in your BRD toolkit. Some recommendations I make regarding vaccines are as follows:

  1. Buying cattle (especially younger cattle) from multiple sources and co-mingling
    • Bovishield MH (a vaccine for one of the most common bacteria involved)

OR

  • Bovilis MH + IBR (two doses but protects against the main virus as well as one of the most common bacteria involved)
  • Cattle that you have bought as above that are likely going to go to a feedlot
  • Bovilis MH + IBR (a vaccine for the most common virus and one of the most common bacteria involved), requires 2 vaccinations, minimum 14 days apart but up to 180 days apart. Feedlots will often pay a premium for cattle that have been vaccinated but please check first as it may depend on when the cattle are vaccinated.
  • Bovishield MH (helps protect against one of the most common bacteria involved)
  • Homebred cattle, no introductions, likely going to a feedlot
  • Bovilis MH + IBR (usually 4 weeks prior to feedlot entry – but check with your buyer)
  • Start of a BRD outbreak
  • Rhinoguard – intranasal vaccine for IBR virus, 1mL up each nostril (as opposed to 2mL in one nostril), faster protection than the Bovilis MH + IBR or Bovishield MH but more handling. Rhinoguard can be used in conjunction with the single shot Bovishield MH.
  • Middle to end of BRD outbreak
  • Debatable as to usefulness of vaccination as exposure and immunity have likely occurred.
  • Better off focusing on pulling and appropriate treatment of sick animals.

If you have any questions about preventing or diagnosing BRD please contact your local vet to discuss. Remember to ask lots of questions about the stock you are purchasing and ensure your agent is keeping in mind the risk factors outlined above to avoid a BRD outbreak in your herd.