Veterinary Drug Handbook (VDH) is the reference veterinarians turn to when they want an independent source of information on the drugs that are used in veterinary medicine today.

Low passage vaccine

A low passage vaccine contains virus particles which have been attenuated, or weakened, less than those in the 'average' vaccine. Low passage vaccines can generally elicit an immune system response in young animals who have a maternal antibody level that would prevent them from responding to an 'average' vaccine.