Q&A: protecting your herd from IBR

Infectious bovine rhinotracehitis (IBR) is a virus that affects cattle causing a number of symptoms. It is most frequently associated with pneumonia. It is estimated that 70% to 80% of Irish beef and dairy herds have some level of IBR exposure. From my personal experience, that figure is lower but it can vary region by region.

It is a significant disease at farm level and also because of its implications around trading as more countries aim to eradicate it.

As Ireland looks at strategies to potentially implement a control or eradication programme I would encourage farmers to be one step ahead. Controlling IBR at herd level makes sense, so let’s try to understand the disease.

What are the symptoms?

Like many other viruses there are a number of strains but the main one causes respiratory symptoms and rarely abortion. We can never say from symptoms alone that an animal has IBR. Like many pneumonia viruses, it causes high temperatures, heavy breathing, poor appetite, milk drops, nasal discharges and abortions among other symptoms.

It is known to cause reddening of the soft membranes of the eyes, nose, throat and windpipe. This irritation of the upper airways can sometimes cause coughing and often opens the door for bacteria to cause secondary pneumonia.

How does it spread?

It spreads in aerosol, mostly from respiratory secretions in cattle in the same airspace or in contact. It is mainly spread by sick animals coughing at a distance of up to 3m to 5m away.

Why is it different?

IBR is a herpes virus like the common cold sore virus and this virus has the ability to become latent. So an animal that comes across the virus can get sick or more often won’t get sick but the virus becomes latent. Latency is where the virus lies dormant in their nervous system, only being shed again at a time of stress.

This is a very important component of how the disease is spread or potentially brought into a herd.

Think about a bought-in animal that looks healthy but gets stressed going through the sale process. If they are latent carriers they then begin shedding the IBR virus in the new herd, infecting more animals. These are often the ones that become sick or latent continuing the spread.

The most shedding of virus is done by sick animals but latent animals can also spread the infection.

How do I treat it?

The severity of the disease will vary hugely with some animals getting very sick, while others will show only minor symptoms. They should be treated with anti-inflammatories and fluids and antibiotics should be used to treat any bacterial infections that can compound IBR.

What happens when an animal is infected?

They can get sick and show symptoms which require urgent treatment or they show no symptoms but become latently infected and can often shed the disease when stressed again in the future.

How can I test for it?

Animals with clinical disease can be swabbed and a sample sent directly to the lab. These swabs must be carried out by your vet. Deep swabs are best, taken at the back of the nasal passages.

Individual animals can also be blood-tested for IBR antibodies, which give an accurate indicator of exposure. You will rarely have animals that have negative antibodies but have been exposed, but for the most part they show exposure.

As a rough rule, it takes about 21 days after exposure for an animal to show rising antibodies for IBR.

We can also test milk from an individual cow and we can check the bulk milk sample for herd level exposure. For the dairy farmer, regular monitoring of IBR antibody levels in bulk milk is a great tool, along with clinical symptoms and strict biosecurity.

How can I stop buying it in?

Any animal coming in can be latently infected (they look healthy) and can start shedding the virus. When you have an IBR-free herd, you should consider testing and isolating bought-in stock.

What effect has it on a beef herd?

It can have a significant effect on beef herds causing pneumonia around calving time in suckler cows. It can also contribute to weanling pneumonia and pneumonia at housing.

The disease causes losses from dead animals, but mostly production losses and higher treatment costs.

What effect has it on a dairy herd?

It can be associated with similar signs to the beef herds with sick cows around calving or times of stress. It can also be associated with milk drops and occasionally isolated as a cause of abortion. It can also cause pneumonia in younger stock, particularly around housing time or when there are other stressors such as lungworm infections affecting the herd.

What is my best vaccine option?

There are a number of vaccine options on the market. They are marker vaccines, meaning when we test animals we can differentiate between the wild virus and the vaccination antibodies.

There are annual vaccination programmes, as well as a six-month live IBR vaccination programme. Most require two shots or some sort of primary course.

There is no template for the best option for your farm. Most importantly, when deciding on an IBR vaccine, handle, store and administer it correctly and at the right time – usually before the main risk period.

Any closed herd vaccinating correctly for IBR for over three to four years should have an extremely low risk of disease

Should I worry about IBR if I have no symptoms?

IBR can be in your herd without any symptoms, so it can be hiding for want of a better word.

Some herds that are negative must focus on keeping the disease out.

It is well worth beef and dairy herds having some idea about what level of exposure they have.

Beef farmers can carry out blood tests on some of the herd to check for antibody levels. We do this at the time of the TB test and monitor 10% of the herd or a minimum of 10 animals in a big herd.

While this is not the ideal number, I got good compliance and it was a reasonable starting point.

If you can show your herd has a lot of evidence to suggest it is free from IBR, surely it adds some value when selling replacement stock to other herds.

I’m selling semen. What are my options?

Care must be taken in terms of IBR control when animals going to stud or for semen collection.

The aim is to have IBR herd-free status and animals that are vaccinated cannot be submitted for semen collection.

Use strict biosecurity around potential stud animals with all equipment, as well as people and other animals that come in contact with them.

How do you control IBR?

Find out what the status of your herd is first. If it’s clear, then very strict biosecurity is an option. Most Irish herds with a known risk or some level of exposure should consider vaccination now to reduce the risk.

A robust biosecurity plan to keep the disease out, combined with a well-planned vaccination programme, makes sense.