What clinical signs indicate highly pathogenic avian influenza in chickens and turkeys?

Highly pathogenic avian influenza (HPAI) is known to cause a variety of clinical signs in infected poultry, particularly in chickens and turkeys. The presence of neurologic and respiratory signs, along with decreased egg production, is characteristic of HPAI infection.

Neurologic signs may manifest as tremors, incoordination, or sudden deaths, which indicate the virus's impact on the nervous system. Respiratory signs, such as coughing, sneezing, and difficulty breathing, highlight the virus's effect on the respiratory tract. These symptoms result from the virus's ability to attack multiple systems within the bird, leading to severe and rapid onset of disease.

Additionally, decreased egg production is a significant clinical sign, especially in commercial layers. Infected birds may stop laying eggs altogether or produce fewer eggs, often with poor quality. This decrease affects not only the health of the birds but also has economic implications for poultry producers.

Other options listed do not align closely with the well-documented signs of HPAI. Difficulty chewing and swallowing, while impactful, is less typical; matting and feather loss are not specific indicators of HPAI; and constipation and abscesses are not relevant clinical signs associated with this particular viral infection.