In a poultry flock with acute mortality and clinical signs ranging from none to conjunctivitis, depression, neurologic and respiratory signs, which diagnoses should be considered?

• A. A, B, And C
• B. Highly Pathogenic Avian Influenza And Newcastle Disease
• C. Marek's Disease And Infectious Laryngotracheitis
• D. Fowl Cholera And Marek's Disease

Answer: (D)

When a flock shows sudden deaths along with a range of signs from mild to conjunctivitis, depression, neurologic and respiratory issues, think of two processes at once: a septicemic bacterial disease to account for the acute mortality and a viral syndrome that can cause neurologic and ocular signs. Fowl cholera, caused by Pasteurella multocida, fits the acute mortality pattern well because septicemia can lead to peracute deaths with rapid decline and systemic signs. Marek’s disease is a herpesvirus infection known for neurologic manifestations such as paresis or ataxia and for ocular involvement that can include conjunctivitis or other eye signs. Together these two diseases explain both the sudden deaths and the broad spectrum of clinical signs observed in the flock. The other pairings either emphasize diseases that don’t fit the full presentation as neatly—such as combinations that emphasize mainly respiratory or neurological signs from a single viral infection—whereas the combination of fowl cholera and Marek’s disease best accounts for the described acuteness plus diverse signs. In practice, pursue sampling and testing to confirm Pasteurella involvement and Marek’s disease, guiding targeted treatment and control.