within the cattle population in Ireland. Most herds have at least one or
more latently infected animals on farm. It is estimated that between
70-80% of Irish herds are infected. The presence of circulating IBR
virus within the national herd can be a barrier to international trade in
livestock and semen, particularly to countries which have eradicated
the disease or categorised it as notifiable.
All ages are susceptible and once infected with IBR, animals become
carriers for life and can shed the virus at any time, especially during
stressful periods such as calving. Latently infected animals act as a
reservoir and are the main source of infection within herds.
IBR virus can spread rapidly between animals through aerosol
transmission, therefore, all animals during the housing period are at
risk. This highly contagious respiratory pathogen can cause disease
resulting in huge economic losses at a farm level through lack of
production and treatment costs. Signs of IBR include runny noses,
milk drop, discharge from the eyes and coughing. Infection usually
results in a high body temperature also. Infection with IBR virus
can lead to secondary bacterial invasion and is responsible for high
treatment rates in a ected groups. All animals infected with IBR virus
become latently infected for life.
Identification of IBR virus within a herd can be performed either due
to an outbreak of disease or for surveillance purposes. Animals can
be tested to either detect the virus itself or viral antibodies against
it. Tests for the virus are usually performed on swabs taken from the
nose, eye and throat of an animal. A positive virus test result indicates
that the animal was shedding virus when the swab was taken.
Following infection of IBR animals will shed virus for around 10 to 20
days before becoming latently infected.
Blood sampling can be useful to detect antibodies. The first sample
should be collected during the clinical phase and a second blood
sample taken 4 weeks later.
Bulk milk sampling can be a useful monitoring tool in dairy herds.
A negative result usually indicates a low number of latent carriers
contributing to the tank (<20%). A positive bulk tank result will be
achieved in herds with moderate to high prevalence of latently
infected animals, recent circulation of the virus or herds that have
been recently vaccinated using a non-marker vaccine.
Early isolation of a ected animals and supportive therapy is useful to
control a disease outbreak. Strict biosecurity measures and adequate
fencing are key tools in reducing the chances of neighbouring stock
infecting your herd and avoiding entry of disease. For open herds
such as feedlots or closed herds such as suckler and dairy units,
vaccination plays a vital role in boosting immunity to IBR virus prior
to exposure. The use of live IBR vaccines can help to reduce virus
shedding and reduce transmission rates during an outbreak. A benefit
of vaccination is that it can also help to reduce the severity of clinical
signs during an IBR outbreak.
the risk of disease within each herd. In the
absence of virus circulation among the
young calf group, vaccination can begin
at the age of three months, revaccination
six months later and all subsequent
revaccinations within twelve months.
This will provide continuous protection
against IBR virus and minimise the number
of animals that become latently infected
carriers. Herds that have a high prevalence
of IBR, are high-risk and/or have clinical signs are best to remain on
a six-monthly vaccination programme until IBR is under control. If
vaccination needs to be carried out before the age of three months
(high prevalence/high-risk herds/disease in calves) then intranasal
vaccination is recommended. An intramuscular vaccination
programme then commences at three months of age.
vaccine it is important to recognise the risk of an outbreak within
your herd with your vet. High risk herds include those that have had
clinical cases of IBR, open herds (especially without a quarantine
procedure), mixing stock from di erent farms (including contract
rearing operations), poor boundary fences, (IBR can spread for up to
5m across fences), bringing cattle to and from the mart, attending
agricultural shows or the presence of farm workers who are in
contact with other stock.
High risk herds should adopt a live vaccination protocol whereas
low risk and pedigree herds can use an inactivated IBR vaccine.
Several studies have shown that live IBR marker vaccines provide
better protection against clinical signs than inactivated vaccines. Less
shedding of IBR virus occurs in animals that have been vaccinated
with live vaccine compared to animals that had received inactivated
vaccine. Therefore, in an outbreak, there is a reduction in the number
of new cases in herds vaccinated with live IBR vaccines such as
pathogens is desirable.
As a labour-saving advantage, Bovilis
need to be selected. Draw up approximately 4ml of Bovilis
before removing the mixture and
inserting it back into the Bovilis
receive 2ml of the solution, injected
into the muscle as a booster dose.
contact your local vet or check out
calves from two weeks of age. When the first vaccination is given between the age of 2
weeks and 3 months, a second vaccination should be given at an age of 3-4 months.