Seeking a diagnosis allows treatment to be refined or future prevention to be managed more effectively. Essential questions are:
- Is IBR involved? If so immediate vaccination can be justified.
- Is there antibiotic resistance in the bacterial component? If so the antibiotic may need to be changed.
- Has the appropriate antibiotic been selected for the species of bacteria that predominate?
- Have viruses been involved? The vaccination programme for next year or for successive batches of cattle can be altered.
Nasopharyngeal or ocular swabs for IBR fluorescent antibody test (FAT)
Sample at least 4 animals into virus transport medium (transport media and BAL kits are available from your local Disease Surveillance Centre), using long guarded swabs for the nasopharynx. Select animals that are febrile and have a clear nasal discharge.
Nasopharyngeal swabs for bacteriology
Sample at least 4 animals into bacterial transport medium again using long guarded swabs. If you require screening for Mycoplasma, submit a duplicate set of samples in Mycoplasma transport medium (transport media and BAL kits are available from your local Disease Surveillance Centre).
Paired serology - Acute and Convalescent samples collected 14 - 21 days apart
Sample 6 animals if greater than 4 months old
Sample 12 animals if less than 4 months old - the presence of maternal antibody in these animals reduces the chances of seroconversion occurring and the larger sample allows for this.
Remember to be precise with sample identification as acute and convalescent samples must be matched to the individual animal.
For definitive virological examination, Broncho-Alveolar Lavage (BAL) on very early cases is necessary
Select four animals that are febrile, have a clear nasal discharge and show minimal depression, ie very early cases. Samples collected can be used for RSV and PI3 FATs with a high degree of success. Note that for your client there is a clear price advantage to this approach when compared to paired serology, and results are available within 24 hrs, as opposed to 3 to 4 weeks.
Remember that in some cases lungworm may be involved
The simplest approach in immature animals is to ensure appropriate anthelmintic treatment has been administered. In adults single sample serology or faecal samples can be used to confirm exposure or infection respectively. BAL can also be used to achieve a diagnosis in this condition.
Where deaths have occurred the entire carcase or pluck should be submitted for examination
Failing that telephone and discuss with a Veterinary Investigation Officer which samples would be appropriate if performing an on-farm post-mortem examination.