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Airsacculitis
Other Names: Air Sac Cold, Air Sac Infection, Air Sac Syndrome, Air Sac Disease
Airsacculitis is a lower respiratory disease in chickens characterized by inflammation of one or more air sacs. These air sacs are a vital part of the avian respiratory system. Chickens have nine air sacs—thin-walled, balloon-like structures that help circulate oxygen efficiently throughout the body. They include four paired air sacs (cervical, cranial thoracic, caudal thoracic, and abdominal) and one unpaired air sac (clavicular).
When the air sacs become inflamed, their walls thicken and may fill with purulent or caseous (cheese-like) material. This condition is most commonly caused by bacterial or fungal infections, and less frequently by viruses. Common pathogens associated with airsacculitis in chickens include Escherichia coli and Mycoplasma gallisepticum.
Several diseases are commonly linked to the development of airsacculitis:
Avian chlamydiosis: A zoonotic respiratory disease caused by the Gram-negative bacterium Chlamydia. Clinical signs tend to be non-specific and vary depending on the strain and the bird’s immune status but often include nasal and ocular or nasal discharge, respiratory distress, green-colored diarrhea, weight loss, lethargy, and general dullness.
Newcastle disease (ND): A highly contagious viral disease affecting both domestic and wild birds worldwide. It is caused by Newcastle disease virus (NDV), also known as avian paramyxovirus-1 (APMV-1). Disease severity varies widely based on the viral strain, the bird’s age (younger birds are more susceptible), co-infections, stress, and immune status. Different strains may primarily affect the respiratory, digestive, or nervous systems.
Chronic respiratory disease (CRD): Most commonly associated with Mycoplasma gallisepticum infection, CRD is a major cause of respiratory illness in chickens. It typically develops slowly within a flock and leads to persistent, progressive respiratory signs such as tracheitis, sinusitis, conjunctivitis, and airsacculitis.
Aspergillosis: A fungal disease most commonly caused by Aspergillus fumigatus. It occurs in two forms: an acute form (brooder pneumonia) seen in young chicks with high illness and mortality rates, and a chronic form in adult birds, often associated with poor ventilation and moldy or dusty environments.
Ornithobacteriosis: An emerging, highly contagious bacterial disease caused by Ornithobacterium rhinotracheale. This gram-negative organism affects chickens and turkeys worldwide and commonly presents as pneumonia or airsacculitis in affected flocks.
Case 1: Airsacculitis in a Pheasants Outbreaks of respiratory disease were investigated in reared pheasants aged approximately 18 to 32 weeks, released into the semi-wild on four shooting estates in southern England. The clinical signs in the affected birds included swelling of the face and eyes, loss of condition, gasping respirations and coughing. The gross pathology findings included sinusitis, airsacculitis, pleural oedema and lung lesions. The histopathological findings in the affected lungs were characterized by a granulomatous pneumonia. Ornithobacterium rhinotracheale (ORT) was isolated from respiratory tract tissues, and 16S rRNA gene sequencing on three isolates revealed two distinct genotypes, one previously associated with some electrophoretic type (ET) 1 strains and the other a novel genotype that clustered among sequences previously associated with ET 3, ET 4, ET 5 and ET 6 isolates. In each case, ORT was identified as part of a complex of other respiratory agents including avian paramyxovirus type 2, avian coronavirus, Mycoplasma gallisepticum, Mycoplasma synoviae and other Mycoplasma species, Escherichia coli, Pasteurella multocida, other Pasteurellaceae and Syngamus trachea, suggesting synergism with other agents. Exposure to other intercurrent factors, including adverse weather conditions and internal parasitism, may also have exacerbated the severity of disease. Ref
Isolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Identification of the cause and corresponding treatment
Beaufrère, Hugues Diseases of the Respiratory Tract. Current Therapy in Avian Medicine and Surgery Volume II E-Book: Current Therapy in Avian Medicine and Surgery Volume II E-Book (2025)
