How is African horse sickness usually diagnosed in affected animals?

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African horse sickness is typically confirmed during postmortem examination by necropsy because the disease causes distinctive, widespread organ changes that can be directly sampled for laboratory testing. At necropsy you can observe the characteristic edema and hemorrhages, especially in the lungs and around the heart, along with fluid in body cavities and other viscera. Collecting tissues from lung, heart, spleen, and lymph nodes for testing with real-time PCR or virus isolation can definitively identify African horse sickness virus, providing rapid and confirmatory evidence in animals that have died or are euthanized.

Serology can show exposure but isn’t reliable for diagnosing an active infection in the acute phase. Nasal swab PCR is less consistently informative because the virus is not primarily shed in nasal secretions, and blood or tissue samples obtained at necropsy more reliably reflect viremia. Blood culture isn’t applicable since this is a viral disease, not a bacterial one.