Horse Vaccinations

Hendra Virus

The Hendra virus (HeV) causes a potentially deadly viral disease that can be spread from horses to humans. There are no known treatments for Hendra virus.

Hendra virus has only ever been reported in Australia*. It was first detected in Queensland in 1994, more recently it has been reported further south and west of the Great Dividing Range.1-3

Where does the Hendra virus come from?

Fruit bats (flying foxes) are the natural hosts of the Hendra virus.4

How is Hendra spread?

It is thought that the Hendra virus is transmitted from fruit bat to horse via feed contaminated with fruit bat urine, faeces or body fluids.5

Hendra virus can be spread from horse to horse and horse to human through close contact with respiratory secretions and/or blood from an infected horse.5

How can Hendra be prevented?

There are no known treatments for the deadly Hendra virus, but there is now a vaccine available through your veterinarian that can help prevent it. Ask your vet about the Equivac® HeV vaccine for horses.6

Vaccination with Equivac® HeV

What is the Hendra vaccine?

The Hendra vaccine is called Equivac® HeV. It can be used in healthy horses from 4 months of age as an aid in the prevention of disease caused by the Hendra virus.1

How was it developed?

The unprecedented inter-species and geographical spread of the Hendra virus underpinned the need for the development of a safe and effective vaccine.

The vaccine against the Hendra virus was developed through collaboration between the animal health company Zoetis Australia, the national government body for scientific research in Australia CSIRO and the not-for-profit Henry Jackson Foundation.

How frequent is the dosing?

The Hendra vaccine can be given to horses as young as 4 months of age and requires two doses, three to six weeks apart, followed by a booster every six months.

To understand where the Hendra vaccine fits around the other vaccinations your horse requires, the Equine Infectious Diseases Advisory Board have developed an easy to follow vaccination protocol. We recommend you use these guidelines when planning an annual vaccination schedule for your horse.

To calculate your horse's vaccination schedule, try our handy tool here.

What can I expect after my horse is vaccinated?

Protective antibodies against the Hendra virus develop in vaccinated horses approximately three weeks after the second vaccination.

Studies prove that vaccinated horses showed no signs of Hendra virus or disease when challenged with Hendra virus approximately 6 months after their initial vaccination course.

Once your horse is vaccinated, your horse’s details will be entered into the national Hendra vaccination registry, so his/her vaccination status can be verified if needed.

Are there any side effects?

All medicines, including vaccines, may have side effects including reactions such as pain, a rise in temperature or signs of serious allergy (e.g. skin lumps, difficulty breathing, collapse), but these were NOT seen when the Hendra vaccine was tested.

In clinical tests the only occasional side effects seen when the Hendra vaccine was administered were mild transient swellings in the area of the neck where the vaccine was injected. This swelling was more common after the second injection and completely disappeared without the need for any treatment, within a week of the injection.

What are the precautions for use?

The Hendra vaccine is for use as a preventative and NOT as a treatment for Hendra virus disease in horses.

No data exists regarding the safety and efficacy of the Hendra vaccine in pregnant mares or animals intended for breeding; use in these animals must be weighed against the risk of serious illness or death from disease caused by Hendra virus.

Any adverse events should be reported by your veterinarian to Zoetis Technical Services Helpline: 1800 814 883.



What is tetanus?

Tetanus, is an often-fatal bacterial disease caused by the organism Clostridium tetani, which is found in soil and droppings.1,2 It’s found all over the world and can affect humans as well as horses. The bacterium can survive as spores in the environment for long periods of time, and while it is in the soil, it’s harmless. However, the bacteria can enter the body through wounds, particularly puncture wounds, if the wound is dirty. The tetanus bacteria do not need oxygen (they are classified as ‘anaerobic’ bacteria) and so they multiply rapidly in the damaged tissues at the site of the injury. The bacteria produce a powerful nerve toxin, causing distressing symptoms and death in about 80% of cases.1

Risk of Tetanus

The risk of tetanus is pretty much everywhere as the organism that causes it, Clostridium tetani, lives in soil and manure and it enters the body through wounds.1,2

Horses are particularly at risk because of their environment and tendency to injure themselves.2

The good news, however, is that tetanus is not contagious, so it is not passed from horse to horse.

Sources of contamination

  • Horses can become infected through gastric or intestinal ulcers after eating contaminated soil or droppings.
  • Wounds, especially deep wounds, are a key source of infection. Common sites of infection are the soles of the horse’s feet, although even a simple thorn prick can allow the bacteria to enter the body2 Surgical wounds are another possible source of entry for the bacteria.
  • Foals can become infected via their navel where the umbilical cord was attached2
  • The mare’s reproductive tract may also become infected, if it’s damaged or the placenta is retained.

Minimising risk

Tetanus can be avoided with vaccination.2

Ensure your mares are well-vaccinated before having a foal: foals may not respond to vaccines early in life so it is important they receive protection via their mother’s milk.

Remember that humans can get tetanus too, so ensure your own tetanus vaccination is up-to-date.

Vaccination with Equivac® T or Equivac® 2 in 1

Tetanus is a totally and easily preventable disease. Vaccination with ‘tetanus toxoid’ should be used for all horses and ponies2.

You can vaccinate your horse against tetanus with Equivac® T or Equivac® 2 in 1, available from your vet.

Your horse can get this vaccination from 3 months of age. If using Equivac T, initially it is given as 2 doses 4 weeks apart, followed by a booster one year later, followed by boosters every 5 years.

For immediate short-term prevention of tetanus, your vet may suggest Equivac® TAT.

Your horse can get both immediate prevention and long-lasting protection with simultaneous injections of both of Equivac® TAT and Equivac® T.

If suitable, your vet may suggest Equivac® 2 in 1, a combination injection that protects against strangles as well as tetanus. The recommended protocol for this product is in the section on strangles.



What is strangles?

Strangles is a respiratory disease of horses caused by the bacterium Streptococcus equi. It is one of the most common contagious diseases affecting horses worldwide.1

Signs of Strangles

Strangles is highly debilitating.2,3 Horses usually show signs of strangles within 3 to 8 days of becoming infected.2

The common signs of strangles include:1–3

  • A nasal discharge (a greenish, yellow, or white “snotty” discharge)
  • Fever (39–40°C)
  • Difficulty swallowing
  • Loss of appetite
  • Depression
  • Cough
  • Swellings that are a result of abscesses of the lymph nodes in the head and neck region due to an accumulation of pus
  • Laboured breathing due to enlarged lymph nodes – hence, the name “strangles”.

These distressing clinical signs can persist for days, weeks or months. Most horses recover, but they may need to be isolated for 6 to 8 weeks.2

Risk of Strangles

Strangles is a highly contagious disease and is rapidly spread from horse to horse.1, 3 Strangles is spread via the pus or discharge from infected horses’ noses, draining lymph nodes, or by coughing.2

Direct contamination

  • Direct contact among horses2
  • Nose-to-nose contact with neighbouring horses or contamination via flies2

Once infected, horses can shed the bacteria for weeks or months (and occasionally years), even after recovery, potentially infecting other horses.2

Indirect contamination

  • Contaminated grooming equipment, shared tack or rugs2
  • Contamination via human contact or contaminated clothing3
  • Sharing of feed or water contaminated by nasal discharge or pus from an infected horse2

The strangles bacterium can survive in the environment for weeks or possibly months, causing an ongoing risk.3

Strangles is a notifiable disease in some States – if your horse is affected, check with your vet to see if you need to report strangles to your local authorities.

Vaccination with Equivac® S

Vaccination is recommended to help avoid this serious condition.1,3

You can vaccinate your horse against strangles with Equivac S or Equivac 2 in 1, available from your vet.

Your foal can get this vaccination from 3 months of age. Initially, it is given as 3 doses no less than 2 weeks apart, followed by annual boosters to maintain immunity. Increased protection against strangles may be obtained by giving booster doses more frequently, for example every 6 months

Equine Herpes Virus

What is Equine Herpes Virus?

Equine herpes virus (EHV) is found in horse populations worldwide.1 There are different strains of the virus, the most common being EHV-1 and EHV-4.1

EHV-1 can cause respiratory diseases, especially in young horses, neurological diseases, and abortion.1 EHV-4 causes respiratory disease and may cause abortion in some mares.1 EHV can persist in the horse with reactivation and shedding of virus occurring during periods of stress.

Signs of Equine Herpes Virus

If your horse is infected, you may notice the following signs:1

  • fever, which may be the only sign in some cases, and may be missed if the horse’s temperature is not measured
  • coughing
  • nasal discharge
  • abortion, which usually occurs without warning, late in the pregnancy.

The respiratory disease caused by EHV most commonly affects young horses.1 Shedding via respiratory secretions typically lasts 7-10 days but may be longer, with aerosol being the primary means of transmission, either directly or indirectly through poor hygiene.

Mares that have aborted also shed virus in respiratory secretions with virus also being present in the foetus, placenta, foetal membranes and foetal fluids. Affected foals that are born alive typically die within days. A single abortion can be a precursor to abortion outbreaks.

The neurologic disease caused by EHV-1 infection is known as equine herpes virus myeloencephalopathy (EHM), and is due to damaged blood vessels, including damage to the blood-brain barrier.

EHM may occur without any signs of respiratory disease and commonly affects the hind limbs and the urinary system.

Signs include:1

  • lack of co-ordination
  • urine retention
  • incontinence
  • inability to stand up, if severely affected.

If your horse is only mildly affected, there’s a good chance of recovery, but there’s a poor outlook for those that have been severely affected. It may take several weeks or months to recover from neurologic problems, and some horses are affected for the rest of their lives.

Vaccination with Duvaxyn® EHV-1,4

You can vaccinate your horse against equine herpes virus with Duvaxyn® EHV-1,4, available from your vet.

Vaccination reduces the clinical signs of respiratory diseases caused by both strains of the virus, EHV-1 and EHV-4.

It also helps to control EHV-1 abortion when used in conjunction with appropriate management practices, as advised by your vet.

Your horse can get this vaccination from 5 months of age, or from 3 months if at high risk of infection. Your horse will need a second dose 4–6 weeks after the first dose, followed by a booster every 6 months.

Breeding mares should receive doses at 5, 7 and 9 months of pregnancy.