One of the saddest problems seen in avian medicine is feather damaging behaviour (also known as feather picking, feather plucking or feather chewing). It is sad for several reasons. Firstly, it is a ‘disease’ of captivity— such behaviour is obviously incompatible with survival in the wild—and secondly, it is a problem that is difficult to cure in that it can often be controlled, but rarely cured.
Knowing that human interaction with birds has caused this problem and that we can’t cure it can be both frustrating and demoralising. Self-inflicted feather damaging behaviour is one of the most common and most frustrating conditions that veterinarians can be presented with. The causes for this condition are often multi-factorial and cascading in their effects. By the time the bird is presented to the clinician the original inciting cause may have disappeared or been obscured by other complicating or reinforcing factors. Feather damaging behaviour may be due to either physical or behavioural problems. It is simplistic and inaccurate to diagnose ‘boredom’ or ‘fear/anxiety’ without a thorough investigation to rule out physical problems first. It is also simplistic to feel that a single cause exists for each individual case. In many cases several factors, both physical and behavioural, have combined to produce the clinical sign of feather damaging behaviour.
PHYSICAL CAUSES OF FEATHER DAMAGING
Anything that makes a bird’s skin itchy or painful can result in feather damaging behaviour.
Parasites both external (mites, lice) and internal (Giardia) are over-diagnosed as a cause of feather damaging behaviour. Pet shops and some breeders often advise bird owners to treat birds exhibiting feather damaging behaviour for lice. Giardia has only been associated with feather damaging behaviour in Cockatiels yet many case studies report Giardia testing in non-Cockatiel species. Pet birds in particular are rarely affected by parasites. In reality, parasites may make a bird itchy, but rarely result in feather loss.
Dermatitis (inflammation of the skin) and folliculitis (inflammation of the feather follicles) can be due to infections (bacterial, fungal, viral), chemical irritants (eg nicotine absorbed from the owner’s fingers) or allergies. It is still unproven that birds can develop allergies but there is strong evidence that they may be a factor in some feather pickers.
Malnutrition especially caused by an all-seed diet often results in dry, flaky skin that is predisposed to superficial infections with resultant itchiness. Feathers will also become brittle and subject to breakage which may stimulate a bird to chew at them.
Heavy metal poisoning is often implicated as a cause of feather damaging behaviour. However, all reported cases are anecdotal and there is no reliable evidence that it causes feather damaging behaviour.
Underlying painful lesions in the muscles, bones or internal organs can cause a bird to pick at the skin and feathers overlying the painful area.
Reproductive activity perhaps through ovarian and oviductal enlargement and liver changes (vitellogenesis—mobilisation of fat from the liver to form egg yolks) is believed to cause abdominal discomfort that may be seen as feather damaging behaviour of the thighs and ventral abdomen of some reproductively active hens. There are also some species specific conditions that can be seen as feather-picking self-mutilation.
Polyfolliculosis is a chronic condition that can cause multiple small feather cysts in Budgerigars and lovebirds and is often characterised by intense itchiness. Newly emerging feathers have short, stout quills with retained sheaths from which several feathers emerge out of a single, enlarged follicle. There is some discussion as to whether this condition is the cause of the bird’s intense itchiness or is the result of damage done by the bird in response to the itch.
Self-mutilation in African lovebirds (Agapornis species) is an intensely itchy self-mutilation problem affecting the shoulder region and wing membrane of these small parrots. Less commonly it can involve the bird’s groin, chest, back, base of the tail and around the cloaca. At this stage the cause remains unknown. Treatment is often unrewarding. Placing an Elizabethan collar on until the skin wounds have healed can be of benefit but recurrence once the collar is removed is common. Long-term scarring of the wing membrane often restricts the bird’s ability to fly and the affected area often cracks and bleeds when the bird stretches its wings.
Cockatiel feather mutilation syndrome is associated with intestinal giardiasis and has been reported in Cockatiels only. It appears to be less common now than 10 years ago. It is thought that the giardiasis causes an intestinal malabsorption syndrome leading to a vitamin E/selenium deficiency which in turn leads to dry, flaky skin which can progress to episodes of feather pulling, feather loss and itchiness. Other clinical signs include weight loss, depression, ruffled feathers, chronic diarrhoea, neonatal mortality, and weakness. Treating the Giardia is usually effective.
Quaker Mutilation Syndrome observed occasionally in Quaker Parrots is seen as an acute onset of severe self-induced skin trauma which is often directed at the neck and chest and usually unrelated to prior episodes of feather damaging behaviour. Its cause is uncertain and treatment can be difficult as the amount of self-inflicted damage occurring in a short period of time can be overwhelming.
Author: Dr Bob Doneley BVSc FACVSc (Avian Health)
The full article you can read by purchasing Australian Birdkeeper magazine Vol 24 Iss 8 from www.birdkeeper.com.au
Reproduced with permission from ABK Publications and Australian BirdKeeper ©2011