Influenza in Horses

Influenza in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

Most common symptoms

Coughing / Depression / Enlarged Lymph Nodes / Fever / Nasal Discharge / Pain


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Most common symptoms

Coughing / Depression / Enlarged Lymph Nodes / Fever / Nasal Discharge / Pain

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Influenza in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

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What is Influenza?

Equine influenza affects your horse’s respiratory system and can damage the lining and mucus membranes within the respiratory tract in a very short timeframe. The incubation period for equine influenza is only one to three days after coming into contact with the infection. 

It is a highly contagious virus and will spread quickly through a group of horses since it is airborne. If you have a herd and notice one horse with any of the symptoms of equine influenza, quarantine that horse and keep a close watch over the rest of the herd for symptoms. When checking your herd, pay close attention to the very young and senior horses. 

Even horses that have previously been infected with equine influenza can contract the illness again. They only have a natural immunity for about a year and then their immunity levels fall and become more susceptible to equine influenza.

Commonly called the horse flu, equine influenza is a viral infection that is very common around the world. Younger horses, generally one to five years of age, are most susceptible.

Symptoms of Influenza in Horses

Equine influenza is an extremely contagious virus. If you notice any of these symptoms, quarantine the sick horse from all other horses and contact your veterinarian immediately for an appointment and treatment.  This is an airborne virus so do not house a sick horse in the same barn as healthy horses.

  • Nasal discharge
  • High fever
  • Deep, dry cough
  • Depression
  • Not eating or drinking
  • Muscle pain, unwillingness to walk or move
  • Enlarged lymph nodes
  • Pneumonia

Causes of Influenza in Horses

Equine influenza has several different strains that can affect horses. The most common strain is Type A influenza. Every strain of equine influenza is airborne and can spread quickly among a herd. In some instances, a horse will be a carrier of the illness, never presenting any symptoms; carriers are still very contagious even though they appear healthy. You may never realize that you have a carrier within your herd. There are no definitive tests that can be conducted to identify which horses are carriers.

Diagnosis of Influenza in Horses

Your veterinarian will conduct a full physical examination. This will include listening to your horse’s lungs and heart as well as noting all symptoms. A presumptive diagnosis will be made based on the symptoms. Equine influenza does have similar symptoms to other respiratory viral infections but treatments for all viral respiratory diseases are the same and further testing is not required.

Further testing may include a complete blood count, urinalysis, and nasal swabs. Most veterinarians will not do additional testing, instead, they will determine that it is a respiratory infection and start treatments immediately.


Treatment of Influenza in Horses

Your veterinarian will set a treatment plan for treating your horse for equine influenza. While there is no treatment that will kill the influenza virus, supportive care and management of the virus are the best option when treating an affected horse.


Your horse should be rested for at least six weeks to allow any damaged tissues within the respiratory tract to fully heal. Stall rest is best, just remember to keep the infected horse quarantined from other horses.

Cleanliness and Ventilation

While your horse is being rested, keep their stall clean with dry bedding. Also ensure that the barn is well ventilated. Excessive dust can cause adverse effects to a horse suffering from equine influenza.

Antibiotics and Other Medications

Your veterinarian will prescribe antibiotics if your horse has contracted a secondary infection, such as pneumonia. Medications that alleviate any inflammation and thins out mucus within the respiratory tract may also be prescribed.


Start vaccinating your horse for equine influenza. Vaccines for equine influenza can be given to foals as young as four months old and should be given a series of three vaccinations over a six to eight month period. Booster vaccinations should be given every six months until your horse is five years old, then once a year boosters are generally recommended.

Recovery of Influenza in Horses

Your horse should make a full recovery from equine influenza unless a secondary infection was found or your horse had an extreme case of influenza. In these instances, there could be some long term damage to the respiratory system. 

Speak with your veterinarian about any possible long term effects to your horse. Always follow treatment plans as prescribed by your veterinarian. If medications were prescribed, finish all medications unless instructed by your veterinarian to discontinue use.

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Influenza Average Cost

From 459 quotes ranging from $2,000 - $6,000

Average Cost


Influenza Questions and Advice from Veterinary Professionals

Influenza Average Cost

From 459 quotes ranging from $2,000 - $6,000

Average Cost