Influenza-Endell Veterinary Group

Influenza

Equine influenza is a highly contagious viral disease that affects horses, donkeys and mules throughout the world. The virus has an incubation period of 2 - 4 days. There is a sudden onset with pyrexia up to 107oF or 420C which lasts several days, or longer if a secondary bacterial infection sets in. Coughing occurs concurrently and may last several weeks. A slight nasal discharge is present, enlarged glands under the throat and runny eyes are also commonly observed. There is also weakness, anorexia, elevated respiratory rate and general muscle stiffness. Secondary bacterial infections can exacerbate these symptoms.

Slight infections can result in recovery after 2 - 3 weeks, however severely infected animals can take up to 6 months to fully recover.

Diagnosis is by observing the clinical signs followed by laboratory analysis to isolate the virus or specific antibody titre determination.

Prevention of the disease is by vaccination.

There still seems to be much confusion over the rules and regulations with regard to vaccinations against equine influenza. In 1980 the rules of racing, initiated a compulsory vaccination program which has been copied by most competition and show horses . The rules stipulate that two vaccinations are given 21 - 92 days apart followed by a third vaccination 150 - 210 days later. Annual boosters are given thereafter. They are allowed to compete after the initial two vaccinations providing the time for the third has not expired. Horses are not allowed to compete within 7 days of receiving the vaccine. Most governing bodies that control the various competitions adhere to these rules, but from time to time these can alter so it is also recommended that checks are made to ensure that the vaccination policy complies with the individual ruling.