Which combination is included in the differential diagnoses for sick birds, including birds with respiratory and neurologic signs?

• A. Avian influenza and virulent Newcastle’s disease
• B. Lead toxicity and calcium deficiency
• C. Pacheco’s disease and salmonellosis
• D. All of the above

Answer: (D)

When evaluating a sick bird with respiratory or neurologic signs, you consider a broad differential that spans infectious diseases, toxins, and nutritional/metabolic disorders, because such presentations can arise from multiple etiologies that affect the respiratory tract, the nervous system, or both. Viral infections like avian influenza and virulent Newcastle disease commonly involve the respiratory system and can produce neuro signs such as tremors or torticollis, so they are essential to include. Lead toxicity is a classic neurotoxic cause in birds, with ataxia, tremors, weakness, and behavioral changes, while calcium deficiency can lead to neuromuscular dysfunction and related signs that may accompany systemic illness. Pacheco’s disease, caused by a herpesvirus, can present with systemic illness and neurologic signs in some cases, and salmonellosis can cause septicemia with varied signs, including respiratory distress and neurologic involvement in severe disease. Because each category can manifest with overlapping signs, all of these types belong in the differential for sick birds with respiratory or neurologic signs.