Vaccination lesions

General description

Vaccination lesions are reactions, such as an abscess or scar tissue, at vaccination sites. Sheep vaccinated with the Gudair® OJD vaccine often develop a large vaccination reaction at the injection site.


  • Incorrect vaccination technique, e.g. not placing the injection correctly.
  • Vaccinating wet sheep
  • Unhygienic vaccination equipment/processes

Clinical signs

  • Firm swelling usually develops at the site of injection, followed by a nodule 7–15 days later.
  • In a small proportion of animals, the lump may be more than 5cm in diameter or develop into an abscess and burst, which may predispose to flystrike.


  • Correct vaccination technique.
  • The vaccine should be administered subcutaneously high on the neck behind the ear.
  • Producers should avoid vaccinating sheep which will be slaughtered as lambs.

Learn more

Fact Sheet - Vaccination Lesions

Best Practice Vaccination for Lambs