What is equine influenza? How do you help to prevent it.

Influenza ("flu") in horses is caused by the equine influenza virus. Influenza is easily transmitted from horse to horse. However, equine influenza virus cannot infectpeople, and human influenza cannot infect horses. Infection typically occurs when a susceptible horse inhales the virus in droplets of respiratory secretions from infected horses.

Stress is an important factor in influenza infection. In the 1989 epidemic of influenza in the United Kingdom, heavily stressed race horses became infected, but less stressed breeding stock and foals nearby were not affected. In some horses, heaves (chronic obstructive pulmonary disease) begins after an episode of influenza that never completely resolves. Rarely, severe diarrhea and purpura hemorrhagica can develop after a bout of influenza.

Clinical Signs

Influenza causes sudden onset of high fever, depression, inappetence and a harsh dry cough. The nasal discharge is initially minimal and watery, but secondary bacterial infection can produce a purulent (snotty) nasal discharge. Lung inflammation and heart abnormalities occur in some infected horses. Coughing can last for 4 to 6 weeks.

Prevention of Influenza

Vaccination: Vaccination against influenza is not 100% protective. Vaccination can diminish the effects of influenza infection but does not protect against influenza virus types not included in the vaccine. Immunity lasts only 3-4 months.

General guidlines:

Foals: vaccinate at 2 months of age and booster one month later.

Mature horses: varies depending upon risk of exposure but should be given at least every 6 months.

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