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“Good vets are just too busy to report adverse reactions to Hendra vaccines.”
When I read these type of statements by well-known people in our Australian performance horse industry and hear many a heated discussion on horses having extreme side effects, including dying, from being administered the drug, I wonder how vets and owners could in good conscious could keep up the six monthly vaccination regime.
The Hendra vaccine was made available for use in Australia firstly under an Australian Pesticides and Veterinary Medicines Authority (APVMA) permit in 2012, and then registered on 04 Aug 15. Whilst the various regulatory bodies in the Australian equine performance industry determine whether the vaccine is mandatory or optional for participation in events, reporting of adverse reactions was mandatory under the APVMA permit policy, firstly by the administering veterinarian to Zoetis and thence to the APVMA. Now that the vaccine is registered, anyone can report an adverse reaction directly to APVMA.
367,759 doses of the Hendra vaccine were administered under APVMA permit until 30 Jun 15. Seven deaths were reported as possibly being attributed to the administering of the vaccine because of timing of the two events. However, a definitive association between the signs and symptoms of the horse and the known pharmacology and toxicology of the product could not be made. No deaths were directly attributed to the administering of the vaccine. The APVMA reviewed the adverse reactions reported during the vaccine’s APVMA permit period and classified them according to probable, possible, unknown and unlikely as reported in Table 1. The full definitions of these categories are included on the APVMA website.
Table 1: The number of equine reports classified by the APVMA to 30 Jun 15
The side effects reported during the period included swelling and soreness at the site of vaccination, increase in body temperature, lethargy and muscle stiffness and swelling in the joints (oedema) now form part of the potential side effects listed on the approved label for the APVMA registered product. Three specific safety warnings have been included in the registration of the vaccine in relation to pregnant or breeding mares, sick or immunocompromised horses and concurrent administration of different vaccines.
The incidence of reaction, the number of probable or possible side effects that occurred in the total number of doses of the vaccine, was also assessed by the APVMA. Injection site reaction, for example, had the highest rate of incidence at 0.18%. Muscle stiffness had a reported incidence of 0.02%.
The APVMA have an established system for reporting an adverse reaction, an unintended or unexpected outcome, associated with using a registered product in accordance with the product instructions. Anyone can submit a report to the APVMA, to the administering veterinarian and/or the product manufacturer.
If you have any concerns regarding the administering of the vaccine for your horse, please contact Willow Wise Therapies or your local veterinarian .