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Home:Equine Diseases:Influenza

Equine Diseases - Influenza



Equine Influenza is a serious viral affecting the upper and lower respiratory tract. It is extremely contagious and has devastating effects on a horse's performance. After contracting the virus, your horse will start to show symptoms of equine influenza within a couple of days and will be contagious for a further five days.

Equine influenza has an almost 100% cross-infection rate in a group of unvaccinated horses which have not been previously exposed to the equine influenza virus. The incubation period of the virus is between one to five days.

Horses usually fully recover from equine influenza quickly (two to three weeks) but if the attack is more complicated it could lead to permanent lung damage.

Equine influenza is extremely debilitating to your horse, leaving it susceptible to secondary

infections such as bronchitis or bacterial pneumonia .

It is imperative therefore that you get your horse vaccinated against equine influenza regularly. The equine influenza vaccine is available combined with the tetanus vaccine giving your hose protection against the two diseases at the same time. Pregnant mares can be vaccinated and it is usually recommended that they be vaccinated 4-8 weeks before the foal is due to be born. There can be side-effects such as local swelling or abscess at the injection site. Very rarely, there can be an allergic reaction which would require emergency treatment from your vet.

Competition horses are required to be vaccinated every 6 months with fines applying to owners who do not comply.

Vigilance over equine influenza is highly maintained in the form of an equine ininfluenzaenza programme. Swab samples from infected horses are constantly monitored in order to isolate and identify the strain of virus that is causing the disease. If a new variant virus arises vaccine manufacturers are advised so it can be incorporated into vaccines to ensure that they remain effective.

Good management and stable hygiene will protect your horse further from the chances of contracting equine influenza. For example,

•  hand wash frequently

•  sterilise buckets, troughs and other equipment

•  minimise contact with other horses

•  if boarding, make sure there is a policy of requiring all boarders to be up to date on their influenza vaccinations

By taking these precautions, you will help to contain the spread of the equine influenza virus. Even if other horses seem healthy, they can shed the virus before showing symptoms of the disease.


Symptoms can include

  • the sudden onset of a frequent harsh, dry, racking cough that can last for several weeks
  • a high temperature - 39-41C (103-106F)
  • slight enlargement or tenderness of the sub-mandibular lymph nodes
  • a clear watery discharge from the nostrils turning thick and green/yellow in colour
  • a discharge from the eyes
  • loss of appetite
  • depression
  • rapid breathing
  • poor performance

The causes of equine influenza are

•  the equine influenza virus the two main strains being equine-1 (H7N7) and equine-2 (H3N8)

•  inhalation of the equine influenza virus released into the atmosphere

•  contact with infected horse

•  contact with infected equipment


Consult your vet and if equine influenza is diagnosed, treatment will probably be recommended as follows:

•  Isolation of your horse from any other horses or animals

•  Medication to help breathing

•  Fever Reducers

•  Antibiotics if a second bacterial infection is present

•  Complete rest

•  Adjustment of food - soft feed and soaked good quality hay is preferable as this can be swallowed without too much pain.

•  No strenuous exercise should be undertaken for two weeks after the symptoms of equine influenza have gone.

•  Ensure a clean comfortable draft-free stable with adequate ventilation

•  Minimise exposure to dust and spores as the respiratory tract will be very vulnerable

•  When temperature has returned to normal and recovery is setting in, turn your horse out into a small area for a short period each day

•  Short periods of hand walking can help with circulation, digestion and drainage of influenzaids