In evaluating birds from a flock potentially affected by highly pathogenic avian influenza, would finding no significant gross lesions be consistent with the disease?

• A. Yes
• B. No
• C. Not enough information
• D. Sometimes, but not typical

Answer: (A)

In highly pathogenic avian influenza, the presence or absence of gross lesions is not a reliable sole indicator of infection. The disease can cause rapid death with little or no visible pathology at necropsy, or the lesions may be subtle and confined to microscopic changes. Therefore, finding no significant gross lesions can still be consistent with HPAI, especially when epidemiologic clues (rapid flock mortality, exposure history, sudden clinical signs) and confirmatory lab tests (PCR, virus isolation, histopathology) support the diagnosis. While HPAI often shows specific gross lesions like hemorrhages or necrosis in various organs, their absence does not rule out infection.