By Emma Campbell,
AFBI Veterinary Sciences Division Disease, Surveillance & Investigations Branch
IN the winter months we often see a substantial increase in respiratory disease among the cattle population, precipitated by stress of housing and mixing of animals.
Young animals are at greater risk of serious disease within the herd. With the high costs associated with respiratory diseases in the UK cattle industry, currently estimated to be £80 million annually, there is a need to understand what the causative agents on farm are. An accurate diagnosis of the cause(s) of respiratory disease is essential so that targeted treatment can be given and a vaccination strategy implemented (if appropriate) to help prevent future outbreaks.
Having an accurate diagnosis should benefit the farm long-term, as future outbreaks and losses could be prevented. Therefore, saving the herd owner money by improving animal productivity, reducing veterinary costs and decreasing farm labour.
To aid farmers and vets to control respiratory disease AFBI offers PCR testing for the major respiratory disease viruses in cattle – Bovine Respiratory Syncytial virus (BRSV), Infectious Bovine Rhinotracheitis (IBR) and Parainfluenza virus type 3 (PI3). These viruses can cause disease by themselves or damage the defence mechanisms of the respiratory tract and predispose the animal to secondary bacterial infections of the lungs.
Bovine Respiratory Syncytial Virus (BRSV) is recognised as a major cause of respiratory disease problems usually in calves under two years old. The disease, as a primary infection, causes significant economic losses in livestock farming and its impact is particularly significant in autumn and winter.
The spread of infection is facilitated by crowding and mixing of animals and the peak risk period is when animals are housed during the winter months. Initial symptoms of the disease include elevated temperature, coughing, discharges from the eyes and nose. As the disease progresses animals go off their feed; the breathing rate increases and becomes more laboured which in turn may lead to death of the animal. BRSV is transmitted horizontally by direct contact with respiratory secretions (aerosol infection).
Infectious Bovine Rhinotracheitis (IBRV) is a severe respiratory infection in cattle characterised by infection of the upper airways and fever caused by bovine herpesvirus type 1 (BHV-1). Affected animals go off feed, become depressed and slow to rise, and often stand with the head lowered.
The disease also causes a purulent discharge from the eyes and nostrils. Occasionally, it can cause reproductive organ infections in both male and female cattle, leading to abortions and in rare cases, encephalitis. IBRV is transmitted horizontally by contact with respiratory, eye and reproductive secretions.
Parainfluenza virus type 3 (PI3) results in moderate clinical signs if there is no secondary infections. PI3 acts as an immunosuppressive, predisposing animals to secondary infection and re-infection. As with BRSV, the PI3 virus is transmitted by aerosol infection and by direct contact with respiratory secretions.
AFBI’s highly sensitive rapid test can be performed on the following sample types:
n Nasopharyngeal and tracheal swabs, preferably in transport media (no charcoal swabs);
n Nasal mucus;
n Fresh respiratory tissue samples.
NB: Vaccinated animals may have a false positive PCR result within 15 days of vaccination. Ideally animals should not be sampled within this timeframe, if they are please interpret the results with this information in mind.
Only one sample type is required for testing, a sample should be submitted from each individual animal suspected of having a problem.
Cost – £22 for RSV and PI3 PCR; £35 for IBR, RSV, PI3 PCR.
When completing the submission form you can request either the RSV and PI3 PCR or the RSV, PI3 and IBR PCR.
These tests can be found under the Virus Detection section of the farm animal submission form www.afbini.gov.uk/publications/farm-animals-diagnostic-submission-form
n AFBI also offers PCR testing for Bovine viral diarrhoea (BVD). See website for details.