Aspergillosis is considered one of, if not the most common, causes of respiratory disease in pet birds.
Aspergillosis usually develops gradually within the lungs and air sacs (thin extensions of the avian lungs). Early signs are often subtle, including reduced energy levels, decreased appetite, lethargy, progressive weight loss, or exercise intolerance (easily out of breath). This chronic form usually is a result of long-term stress or illness and often goes on undetected for some time. Respiratory signs, such as increased respiratory rate and effort, open-mouthed breathing and respiratory noises are signs of increasing severity and are not normally detected until late in the development of disease. Respiratory distress can be an emergency in birds and can lead to rapid deterioration or sudden death. If you see these signs, alert your veterinarian as soon as possible.
Although aspergillosis is primarily a respiratory disease, it can affect any organ of the body by traveling through the bloodstream or by growing through an air sac into the body cavity. Because of this, there are a large number of less common signs that may be seen. Gastrointestinal signs, such as diarrhea and regurgitation or neurological signs including tremors, incoordination and generalized weakness have also been reported. Some birds go to the veterinarian with a wing droop secondary to damage to air sacs near the shoulder.
Aspergillosis can be treated with a combination of anti-fungal medication and supportive care with variable success depending on the severity and extent of disease. When considering prognosis it should be kept in mind that by the time many birds show clinical signs they likely have been sick for several weeks.
Anti-fungal medication is the first line of defense against aspergillosis, and of these medications, itraconazole is probably the most widely accepted anti-fungal drug. This medication is given by mouth and is relatively safe for use in birds. Another anti-fungal, amphotericin B, has been commonly used as a primary treatment for aspergillosis in birds when they are hospitalized, but it has been known to cause toxicity, damaging the kidneys when used for long periods. Another use for this drug is that it may be administered topically to an area of fungal growth during the endoscopic procedure, as mentioned above. There are many other anti-fungal medications that are used less frequently with varying success. Nebulization (aerosolization) of certain drugs may also be a reasonable way to treat fungal infection by allowing the drug to gain access to the airways. Anti-fungal therapy may need to be continued for at least 6 weeks and in some cases as long as 6 months in order to be fully effective.
In serious cases, surgical intervention may be necessary. Aspergillus can form granulomas (masses of fungi combined with inflammatory cells) within the airways or other parts of the body. If a granuloma forms within the trachea, it can block air flow. If this happens, the animal may need to be anesthetized so that the mass can be removed. If an airway cannot be established, veterinarians will often place an air-sac cannula (a tube leading into an air sac through the body wall) so that the bird can breathe. In many respects this is similar to the placement of a tracheostomy tube as performed in people and other mammals in emergency settings.Â Anesthesia of a bird with respiratory problems does carry its risks but it may be necessary if the bird cannot breathe effectively.
Aside from treating the disease itself, efforts must also be made to ensure that the bird is otherwise stable. Because of this, supportive care is an important part of treatment. Some birds may need supplemental nutrition if they are not eating. Other problems such as dehydration or hypothermia may also need to be addressed.Â Lastly, it is extremely important to remember that development of aspergillosis is often an indication of an underlying disease or husbandry problem. The cause of immune suppression must be addressed in order to increase the likelihood that your bird will return to health.