Airsacculitis

Airsacculitis is an inflammation of the air sacs in birds, an organ system essential to avian respiration. It can arise from infectious, noninfectious, or mixed causes and may affect one or multiple air sacs, compromising gas exchange and overall health. The condition is most commonly described in poultry and pet birds.

Causes and pathophysiology are diverse. Bacterial infections (for example, Escherichia coli, Pasteurella multocida, or Mycoplasma gallisepticum) are frequent, sometimes as secondary invaders following respiratory disease. Fungal infections (notably Aspergillus fumigatus) can invade air sacs, particularly in damp or poorly ventilated housing. Viral infections, parasitic infestations, physical injury, and exposure to toxins or poor husbandry practices can also contribute. Inflammation leads to thickening and exudation within the air sacs, reducing airflow and causing respiratory distress, reduced appetite, and weight loss.

Clinical signs vary with severity and can include labored breathing, tail bobbing, facial swelling or ventral distention from swollen air sacs, coughing or sneezing, nasal discharge, depression, and decreased egg production in breeders.

Diagnosis relies on a combination of history, clinical signs, and targeted testing. Imaging (radiographs or ultrasonography) can reveal air-sac lesions; sample collection from air sacs or exudates for cytology, culture, and PCR helps identify pathogens; necropsy provides definitive confirmation.

Treatment and management depend on the underlying cause. Bacterial infections are treated with appropriate antibiotics, while fungal infections require antifungals. Supportive care, environmental improvement (ventilation, cleanliness, reduced ammonia exposure), and isolation or culling of severely affected individuals may be necessary in flocks. Prevention emphasizes biosecurity, vaccination where available, and good husbandry to reduce stress and exposure to pathogens.

See also avian respiratory diseases, poultry health, avian mycoses.