Batch safety testing of veterinary vaccines - potential welfare implications of injection volumes

This study examines the volumes administered by injection during the batch safety testing of veterinary vaccines according to the methods laid down in European Pharmacopoeia monographs. These are compared with maximum dose volumes recommended in good practice guidelines. The volumes administered during safety tests frequently exceeded recommended maximums, giving rise to concerns that these tests may seriously compromise animal welfare. This was particularly the case for live liquid vaccines and for vaccines recommended for intramuscular injection. The volumes used in testing vaccines for avian species exceeded the recommended maximums by the greatest amount. The administration of test doses should be performed in a way that minimises pain and discomfort. The refinement of tests by dividing large dose volumes and delivering them over multiple sites is discussed, but it is recognised that there are technical limitations, which in some cases may cause difficulties with fulfilling the purpose of the tests. Previously, the relevance of batch safety tests has been widely criticised, due to a lack of evidence that they contribute to the safety of veterinary medicines. By showing that the conduct of target animal safety tests can involve injection volumes that compromise the welfare of the animals involved, this analysis highlights the need for a more critical assessment of the necessity and justification for these tests.