Is IBR vaccination worth considering this winter?

Many herds are vaccinating against IBR this winter, with many more asking whether they should they be? I always stress to farmers also that IBR is just one of many diseases that can cause pneumonia in cattle, so is it worth vaccinating for?.

IBR (infectious bovine rhinotracheitis) is a virus that affects cattle and is most frequently associated with pneumonia. It is estimated that 70-80% of Irish beef and dairy herds have some level of IBR exposure. It is a significant disease at farm level and can have implication for trading animals.

As Ireland looks at strategies to potentially implement a control or eradication program for IBR, I would encourage farmers to be one step ahead.

Like many other viruses there are a number of strains of IBR. Most commonly these cause respiratory symptoms, high temperatures, heavy breathing, poor appetite, milk drops, nasal discharges and occasional abortion. IBR is also 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.

In post mortem you will often see the windpipes of these animals has become a darkened red colour.

IBR spreads in aerosol, mostly from respiratory secretions in cattle in the same airspace or in contact. It can spread by coughing (3-5 metres of aerosol is produced by coughing cattle), mostly from animals who are sick.

IBR virus is a herpes virus similar to the common cold sore virus, though it has the ability to become latent. Animals in contact the virus may become sick, though more often they 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 part of how the disease is spread.

Think about a bought in animal that looks healthy, but going through the sale process gets stressed. If they are latent carriers they then begin spreading the IBR virus into their new herd, infecting more animals who often are the ones that become sick.

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

Animals with clinical disease can be swabbed (nasal) and samples sent directly to the lab. These swabs must be carried out by your vet and work by detecting virus, deep swabs at the back of the nasal passages work best.

Individual animals can also be blood tested for IBR antibodies, which gives an accurate indicator of exposure.

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

Milk from individual cows and a the bulk milk sample can be tested for individual or 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.

The severity of the disease will vary massively, with some animals getting very sick, while others will show only minor symptoms. Supportive care such anti-inflammatories and fluids with covering antibiotics to treat any bacterial infections that can compound the infection is recommended.

Any animal coming in can be latently infected (look healthy) and can start shedding the virus. When you have an IBR free herd you should consider testing and isolating bought in stock. That quarantine means they need to be isolated for three to four weeks with no nose-to-nose contact with other members of the herd. Ideally, they should not share the same airspace indoors.

There are a number of vaccine options on the market, including marker, annual and bi-annual.

Marker vaccines allow for differentiation between the wild virus and the vaccination antibodies during testing.

Annual dead and live vaccination programs and six month live IBR vaccines mostly require two shots or some sort of primary course.

There is no definite best option for all farms, different vaccines work for different farmer and most importantly when deciding on an IBR vaccine, handle/store/administer it correctly and at the right time.

As a latent virus, IBR can be present in herds without any symptoms .

Herds that are negative should be vigilant on keeping the disease out.

It is a good idea to do checks to gather data on exposure levels by blood testing a percentage of the herd to check for antibody level.

Having evidence to suggest a herd is free from IBR adds value when selling replacement stock to other herds.

When sending animals to stud or for semen collection its important to be cognisant of IBR control. Animals that are vaccinated cannot be submitted for semen collection. This also means where other animals are vaccinated, particularly with intranasal vaccines, they can cause bulls to have antibodies.

Use strict biosecurity measures to protect potential stud animals with all equipment, people and other animals that come in contact with them.

Knowing how dangerous IBR can be, it would be very hard for any vet not to say that IBR isn't worth vaccinating for. Like many vaccines it is in an insurance policy for what can be a devastating and costly disease.