“Good Vets Are Just Too Busy To Report Adverse Reactions To Hendra Vaccines.”

“Good vets are just too busy to report adverse reactions to Hendra vaccines.”


When I read these statements made by well-known people in our Australian equine performance horse industry and heard many a heated discussion on horses having extreme side effects, including dying, from being administered the drug, I wondered how vets and owners could, in all good conscious, 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 4 August 2015.  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 vet 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 from the vaccine release under APVMA permit until 30 June 2015.  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 each of these are included on the APVMA website.

Table of equine Hendra vaccine adverse reactions reports to 30Jun15

Table 1: The number of equine Hendra vaccine adverse reaction reports classified by the APVMA to 30 June 2015

The side effects reported to 20 Jun 2015 included swelling and soreness at the site of vaccination, increase in body temperature, lethargy and muscle stiffness and swelling in the joints (oedema).  These 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 oedema, for example, had the highest rate of incidence at 0.18% and muscle stiffness, 0.02%.

The APVMA has 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 about a product; make a report to the administering vet 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.



APVMA. (2015). Hendra virus vaccine. Retrieved 28 January 2015, from Australian Pesticides and Veterinary Medicines Authority.

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