Some problems concerning the assay of Clostridium chauvoei vaccine in laboratory animals.

The potency test prescribed for Cl. chauvoei vaccines in the British Veterinary Codex requires the complete survival of a group of immunized guinea pigs and death of all unvaccinated controls. Problems arising from the influence of extraneous factors such as animal strain, diet and seasonal variation on the outcome of this test are discussed together with alternative methods that might permit the use of a standard preparation.