Respiratory disease is a common clinical problem in pet birds and is often a cause for emergency presentation. The improved efficiency of their respiratory system makes birds more susceptible to the effects of respiratory toxins and disease.
Developmental anomalies: Usually apparent prior to weaning, occurring in a single bird in clutch. Choanal atresia is most common, which may be partial or complete. Clinical presentation: serous nasal discharge occurring prior to weaning. Several techniques described for repair.
Nutritional: Hypovitaminosis A: can affect any part of the respiratory system. Epithelium undergoes squamous hyperplasia or metaplasia; linings are thickened; resistance is decreased, leaving a greater opportunity for bacterial and fungal colonization. Clinical signs include any or several of the following: erythematous, swollen choanal slit; blunted/decreased choanal papillae; erythematous nares or larynx; nasal discharge (initially serous); sinusitis. Note: once blunting of choanal papillae occurs, the papillae may not return to normal appearance; therefore blunted choanal papillae alone may be a previous episode.
Foreign bodies: In the nasal cavity, granuloma is most common, but sand or particle irritants, or excessive dirt/dust all can occur. Look for sneezing or nasal discharge, initially serous or mucoid. Within the sinus, granulomas can develop as a sequela to immunosuppressive disorder, hypovitaminosis A, or infection (i.e., Chlamydophila psittaci). Clinical signs include swelling of the sinus region, air inflation of sinus region, and possible conjunctivitis. Sneezing or nasal discharge are variable. Within the trachea, granulomas or seed are the most common foreign material. The most common site for obstruction is syrinx. Clinical signs consist of acute or subacute dyspnea and voice change. In cases of tracheal obstruction, signs can be relieved (usually completely) by placement of an air sac tube. Hyperinflation of air sacs is usually present radiographically.
Inhaled irritants/toxins: Chemical toxins such as fumes or other inhalant toxins may be rapidly systemically absorbed, and often may be fatal.
Infectious agents: Bacterial agents--predominantly gram-negative organisms E. coli, Klebsiella spp., Pasteurella multocida, Pseudomonas spp., and Salmonella spp. gram-positive normal flora such as Staphylococcus spp. and Streptococcus spp. become opportunistic pathogens. Viral agents are rare in association with respiratory disease in pet birds. Fungal agents are commonly associated with respiratory disease. Most common is Aspergillus spp., but other fungal agents, have been identified. Fungal agents are not contagious; rather, an immunosuppressive event or overwhelming load of fungal spores are prerequisite to infection. Chlamydia and Mycoplasma are infectious causes of respiratory disease, among other signs.
Neoplasia: Fibroma, fibrosarcoma, basal cell carcinoma, squamous cell carcinoma, and malignant melanoma
Trauma: Can cause changes in the structure of the beak or sinus and lead to functional respiratory disease.
Abdominal masses: Can interfere with the ability of the air sac to inflate, limiting respiration and causing severe dyspnea, which is unrelated to the respiratory tract. Ascites may have the same effect.
Air sacculitis and pneumonia: These are the most common primary respiratory diseases. Air sacculitis is radiographically characterized by a cloudy appearance to one or more of the air sacs. Pneumonia will appear as an increase in the reticular pattern of the lung, along with peribronchial cuffing. Common etiologies are discussed above.
Orlando Diaz-Figueroa, DVM, MS, Dipl. ABVP (Avian Specialty)