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PCR Sampling

Polymerase Chain Reaction was developed in 1983 and is now widely used for many biological, medical and veterinary diagnostic purposes. It is a technique in molecular biology to look at DNA and RNA. PCR combined with sequencing gives us the sequence of nucleic acids, which can indicate changes compared to vaccine strains. Based on the sequences of nucleic acids we can determine amino acid sequence too.

Firstly the presence of the virus is established and in what quantity. Further testing is then carried out to compare and type the virus against vaccine and field strains. This is also how new viruses are discovered.

The amount of swabs taken will vary according to individual cases.


  • All swabs used need to be plain, sterile swabs. Swabs in the orange tube are suitable for trachea, kidney or caecal tonsil sampling.
  • The plain swabs in the blue tube are best for cloacal sampling as they are larger.
  • Tracheal swabs require the operative to be trained before attempting to sample, otherwise the swabs may be unproductive. Good eyesight helps and also it is useful for someone to assist by holding the bird.
  • When swabbing any tissues it is important that the technique is carried out as aseptically as possible, so wear disposable gloves and keep the swabs in the tube until you need to swab.
  • Air-dry the swabs before replacing in the tube; the purpose of this is to lower the growth of bacteria and moulds in transit to the laboratory.
  • Clearly label each swab and place them in a plastic bag marked with the site name, house number and date so it is clear which submission form they are with.
  • PCR sampling kits are now available at the practice.