Permitted Substances List of the Canadian Standards on Organic Production Systems - CAN/CGSB 32.311 - permit the use of Health Care Products and Production Aids in Table 5.3 under the various categories - "Anti-inflammatories, Biologics (including vaccines), Homeopathic and Biotherapies, Parasiticides and Anti-microbials, Plant oils". 

Click on Health Care Products and Production Aids to get a complete listing of substances commonly used in organic livestock husbandry, along with some specific recommendations of acceptable practices.