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Swine Influenza or Flu (SI)

See chapter 6 for further information.

(292) This is caused by one of 4 or 5 different strains of influenza virus which cause respiratory disease and infertility. If a new strain is introduced into the breeding herd and there is no immunity, the respiratory disease that follows can be quite dramatic. Within 2 to 3 days up to 40 to 50% of animals may be off their feed looking very ill. This can be quite alarming but the rapidity of the clinical signs are almost exclusively confined to this disease. The major risk to the pregnant sows are the high temperatures which cause abortions, embryo or foetal loss, or high stillbirth rates. Widespread coughing and pneumonia may also be seen and individuals should be treated with broad spectrum long-acting antibiotics.

To prevent secondary infections causing complications such as abortions and stillborn piglets it is advisable to treat the breeding herd at the very onset with water soluble antibiotics, OTC or CTC, for a period of 48 to 72 hours. The course of the disease in individual sows is usually 4 to 7 days and within 14 days most animals in the herd have returned to normal. In large herds SI can become endemic with disease appearing every 3 to 6 months. A vaccine is available in some countries.

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