How do allergic reactions in birds differ from those in mammals?

While allergies and diseases of the immune system happen in birds, in comparison to mammals, diseases associated with allergies are much less commonly reported. If you have an issue with a bird that you think might be an allergy, for example - its skin seems itchy, or it is congested and showing upper respiratory signs, it is much more likely to be another problem, rather than an allergy. Birds have mast cells, which in mammals, release histamine – the main mediator of inflammation in an allergy or “type 1 hypersensitivity reaction” in immunology – but, the mechanisms of allergic reactions in birds are still quite poorly understood. Nevertheless, allergic and hypersensitivity diseases are thought happen and they can present in a variety of different ways in birds, but mostly they are thought to manifest in the respiratory tract and in the skin.

How might environmental allergens contribute to the development of Inflammatory Lung Disease in Parrots?

Inflammatory Lung Disease: This has mostly been reported in Blue and Gold Macaws and can cause exercise intolerance, a darkening/discolouration of the facial skin due to reduced oxygen levels and respiratory difficulties. Longer term it can also lead to right sided heart failure in birds. Environmental allergens are suspected to potentially play a role in the development in this condition, but air-born toxins and infectious agents could also play a role. A prevalent theory is that this condition may, in many cases, be triggered by powder-down from other Parrots. In some of the reported cases in the literature, affected Macaws were housed alongside Cockatoos with poor ventilation levels and it is thought that the high levels of dander produced by the Cockatoos, triggered the development of this disease in the Macaws, leading to progressive fibrosis (scarring) in the lungs and a gradual worsening of the signs. Treatment of this condition involves eliminating potential triggers and then giving symptomatic treatment with anti-inflammatories, drugs to dilate the airways (bronchodilators), treatment for heart disease (if applicable) and oxygen therapy as required.

How can Inflammatory skin disease contribute to feather destructive behaviour in parrots, and how often does this occur based on your experience?

Inflammatory Skin Disease: Feather destructive behaviour (FDB) or “plucking” (and auto mutilation) are commonly observed in Parrots. It can be easy to come to the conclusion that the reason for it might be is that a bird is itchy. It can then be easy to come to the conclusion that they are suffering from allergic skin disease. Feather destructive behaviour (aka “feather plucking”) is rarely the result of allergic skin disease, however it can be. Usually, when a bird is plucking at its feathers, it’s best to get a diagnostic panel done to look for potential underlying medical causes. As part of this, blood work and x-rays will often be recommended, however another useful test is the collection of skin biopsies for analysis.

Usually, one biopsy is taken from an affected region and another from an unaffected region that the bird cannot access – particularly the skin in the back of the neck, for comparison by a pathologist.

Where it is present, allergic skin disease can affect young or older birds (delayed onset) and it can be year-round or seasonal.

In my experience, allergic skin disease is a rare cause of feather destructive behaviour in Parrots and in many cases, the cause of the disease is actually a behavioural or enrichment issue, rather than a medical one. Most commonly, it seems related to an inability to exhibit normal foraging behaviours for the length of time that they normally would in nature. A variety of medical problems other than allergies can also potentially be an underlying cause of FDB.

Allergic skin disease can be treated with anti-inflammatories, omega-3 fatty acid supplementation and antihistamines, although in birds, this can be a difficult condition to resolve. The use of steroids, as may be used in humans or other mammals, is not as straightforward in birds as there is a much higher risk of development of significant immunosuppression – birds are therefore much more sensitive to the adverse effects of steroids than many other species.

What challenges are associated with intradermal skin testing in birds compared to other animals?

Intradermal Skin Testing in Birds: Although protocols for this have been described in some species (e.g. Hispaniolan Amazon parrots), it is still considered unreliable. Birds have extremely thin skin and do not respond to histamine as a positive control. Intradermal skin testing is still not considered as a reliable means of allergy testing in birds and more research is needed in terms of being able to interpret results meaningfully in a range of species.

What evidence exists regarding food allergies in birds, and how reliable is it?

Food Allergies: Proof of food allergies in birds is very scarce, however it has been suspected that in some cases, food allergies to ingredients which may also cause allergic disease in mammals (such as certain nuts or grains), has been observed. One of the advantages to feeding organic diets is that they are free of pesticide and preservative residues, which has been touted as a way to reduce the risk of exposure to potential allergens. The truth is – we haven’t got much definitive proof that food allergies are really observed in birds, only reports of a few cases where it has been suspected.

Why is it recommended to consult an avian veterinarian when a bird shows signs of potential allergies?

Conclusions: While they can happen, allergies and allergic diseases are not thought to be common birds. Where they are observed, they mostly seem to manifest in the skin/respiratory tract. Where a bird is unwell, showing signs that could be considered to be an allergy and where there is any doubt, the best advice is to present the bird for an examination by an avian veterinarian. In my experience, in the majority of cases where owners suspect an allergy is the problem – it usually turns out to be something different in birds. We still have a lot to learn about the prevalence of allergic diseases in birds – but at present, we believe that it’s not anywhere as problematic or frequent as is observed in humans or mammalian pet species. It seems much more common to see allergic disease in human owners resulting from pet birds (usually due to excessive exposure to danger and poor ventilation), than it does to see allergic disease in the birds themselves!