Avian aspergillosis – 3 reasons why vets despise it
Updated: Jul 30, 2019
You may have heard in the news about the recent health crisis with the endangered NZ parrot the kākāpō. You can find more here about the scale of the problem in these unique and special birds. The respiratory disease they are suffering is due to a fungal organism, Aspergillus sp. and the disease is called Aspergillosis. It is a well-known disease and a scourge for every avian veterinarian!
Why is fungal disease such a problem for wild birds?
Firstly, the fungus is found in nature. It reproduces by forming spores, which look like a fine powder and can easily be airborne and inhaled. Aspergillus spores can be found everywhere in the environment, but may be concentrated in some areas, such as wood chip piles, disturbed ground and mouldy, damp hay and straw or rotten leaf litter. As such, it is impossible to get rid of it, but care can be taken to avoid unnecessary exposure. Once inhaled, it might cause “granulomas” (lumps) in any part of the respiratory tract or invade other organs via the bloodstream – basically the fungus starts growing inside the bird. It is nasty!
Secondly, it is difficult to diagnose. Birds may lose weight or just appear to be depressed or quiet. By the time respiratory signs show - such as increased respiratory rate, effort or noise - often the disease can be advanced. There is usually an elevated white cell count in blood tests, showing signs of infection. Radiographs (xrays) can sometimes show suspicious lesions, but a CT (computed tomography) scan will give more evidence to confirm the presence and location of fungal plaques. True diagnosis means actually seeing the presence of fungus which means the need for an endoscopy, but usually if we have all of the other signs above, Aspergillosis would be suspected.
Thirdly, treatment is difficult, time consuming and expensive. Birds need to nebulised with antifungal drugs so that the drugs can reach all the air sacs, but also oral or IV antifungal drugs, anti-inflammatories and antibiotics for secondary infections. Critically ill birds may require supplemental oxygen or surgery to help them breathe. Some surgeons will attempt to remove granulomas via surgery. Treatment can take months and is not always successful so it is sometimes kinder to have the bird humanely euthanised if the disease is advanced.
For wild bird care, it’s important to know about this disease and try and catch it early so the bird has a greater chance of survival. Even better is prevention! Not every bird that inhales spores will get sick. Stress is known to be a factor in Aspergillosis and some bird species tend to be more sensitive to stress in captivity – in particular seabirds and penguins. For these birds it is recommended to have them immediately on a preventative dose of antifungals whilst they are in care. A veterinarian would be required to dispense and calculate the correct drug and dose.
Another important consideration is the substrate (flooring) of your aviaries and pens. Ensure that you use fresh pine needles or leaf litter and not any that has been stored in a heap, as there may be “hot spots” of mould. Note that it is not always obvious!
If you do notice any mould, it would be best to get rid of the whole lot, rather than risk using it. Some substrates are worse than others for developing mould and it’s best never to use wood chip or mulch in bird enclosures. Dry pine needles, fresh leaf litter (e.g. from a forest), grass, dirt, pebbles or concrete floors with coverings are best. The substrate you use will depend on your bird species.
If you do suspect respiratory disease in a bird, please take them immediately for assessment to a bird-friendly vet, as time is of the essence if they are to survive.
Dr Janelle Ward
Learn Bird Care was co-founded by Dr Janelle Ward and Mandy Robertson and we offer specialist online courses on wild bird rescue, first aid and rehabilitation.
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