Feather destructive behavior (FDB) is a complex and highly variable suite of behaviors with multiple possible etiologies from "physical" (often termed medical) conditions in which abnormal preening is a clinical sign of another disease process to "psychogenic" (often termed behavioral) disease, where no obvious "physical" disease is diagnosed.
Clinicians should first rule out normal anatomy or physiologic events (e.g., apteria, molting), feather destruction from a conspecific, and diseases that negatively impact feather development (e.g., circovirus, polyoma virus). In addition, a variety of diseases may cause abnormal feathers that can look as if FDB is occurring. Common causes include poor nutrition, inappropriate environment (e.g., small cage or low humidity leading to broken feathers), and mites. There are multiple diseases proposed to have FDB as a clinical sign. Conditions that cause pain or discomfort, such as arthritis, renal disease, skin or internal masses, wound healing, gastrointestinal disease, cardiovascular disease, and bornavirus infection have been linked to FDB by some authors. Pruritus from parasites or suspected allergies may also cause FDB. Inappropriate basic husbandry (e.g., nutrition, humidity, space needs) and physical disease should be identified and appropriately managed.
However, animals engaging in FDB often have no obvious current physical disease or, upon successful treatment of a disease, the behavior remains. Etiologies in these cases are likely multifactorial and may not be clearly elucidated in any individual case. Some proposed etiologies for psychogenic FDB include genetics, lack of opportunity to express normal behaviors (e.g., foraging, social interactions), overly aversive environments, and abnormal neurological development/brain dysfunction. Clinicians should guide caregivers to improve basic husbandry if needed, but also deeply engage in environmental changes that focus on increasing environmental complexity and enrichment (particularly foraging), establishing normal bathing routines, engaging in positive reinforcement training, and significantly reducing even subtle aversive interactions. In some cases, this is adequate to reduce the expression of FDB. In many instances, neuropharmaceuticals are included in the management plan. Medications help normalize brain chemistry, which allows the animal to respond more readily to environmental changes. While likely rare, the behavior may be related to operant learning, where caregiver attention or other environmental stimuli have directly reinforced the behavior.
Feather destructive behavior (FDB) can be a clinical sign associated with another disease process, as well as a condition that presents without any obvious relation to active "physical" disease. Clinicians can take a systemic approach to considering possible etiologies, though should always understand that there can be overlap between conditions. This lecture is focused primarily on psittacines, though the condition is present in other groups.
Feather destructive behavior may be suspected with a wide variety of presentations - from slight damage to coverts in focal area to complete loss of feathers on most of the body. In some cases, active damage to the skin and muscle develops. Caregivers may see birds pulling feathers and over-preening, but in many cases the FDB occurs when the animal is not being observed. In some cases, caregivers are unaware of what normal preening or feather condition looks like and are unaware abnormal behavior is occurring. Conversely, caregivers may be concerned about preening or feather loss that is normal.
Clinicians should evaluate the case to ensure that FDB is occurring and that the condition of the feathers is not related to normal variation or abnormal feather growth/loss without FDB. Reviews are available.7,9,15
Normal anatomy, normal physiologic events, strain variations:
Apteria (featherless tract)
Lutino cockatiel "bald" spot on the back of the head
Abnormal feathers, feather loss, or appearance of feather loss:
Obesity or lipoma (apteria more visible, particularly over coelom)
Circovirus (psittacine beak and feather disease) and polyomavirus
Small cages (break flight/tail feathers)
Low humidity and lack of bathing (retained sheath, brittle feathers, unkempt appearance)
Abnormal photoperiod (delay or abnormal molt, retain old feathers)
Protein deficiency (abnormal molting, poor feather growth)
Mites (feather loss, abnormal feathers)
Hypothyroidism (feather loss, poor molting)
Systemic diseases (abnormal feathers)
Organ failure may impair molt, normal preening, and feather growth
Respiratory discharge from nares may cause secondary focal feather loss
Follicle damage (feathers can't regrow or grow abnormally)
Feather destruction from a conspecific
"Physical" feather destructive behavior:
Referred pain (focal or diffuse)
Renal disease (particularly over synsacrum)
Neoplasia, other masses
Gastrointestinal disease (parasites, bacteria or yeast overgrowth)
Cardiovascular disease, hypertension
Allergic (delayed type hypersensitivity; particularly macaw, Amazon)5
Dermatitis/folliculitis (bacteria, fungus)
Bornavirus (speculative, peripheral neuritis)
Gastrointestinal Giardia psittaci (cockatiel)
"Psychogenic" feather destructive behavior:1-4,6,13,14,20
Proposed categorization of behavior etiology
Maladaptive behavior (attempt of animal to behave normally in abnormal environment)
Excessive/displacement grooming in face of chronic stress
Abnormal time budget (e.g., food acquisition in captivity too quick/easy)
Lack of other behavioral opportunities, limited captive behavioral repertoire
Malfunctional behavior (primary brain dysfunction)
Introduced by environmental factors (e.g., raised in un-enriched environment)
Learning as a source of feather destructive behavior:
Reinforcement from external stimuli gained (e.g., attention from people)
Reinforcement from internal stimuli (e.g., relief from stress)
Psychogenic FDB is associated with captive environments. Captive environments are inherently limited and reduce an animal's choice and control significantly. Birds may be protected from many dangers but they cannot readily engage with a complex environment or utilize their potential full behavioral repertoire. This is exacerbated by current standards of care in most pet situations; food is too easy to get and options for behavior are hard due to limited enrichment (particularly foraging) and social interactions. In addition, most caregivers are not familiar with ways to utilize positive reinforcement to increase desired behaviors and are unaware of or insensitive to allowing animals to choose to not engage in behavior. This leads to an environment that is shifted from being rich in opportunity for positive reinforcement to one that has a preponderance of aversive interactions. This can be very "subtle" and can easily happen in situations where animals are clearly loved by their caregivers.
If FBD, feather loss, and/or abnormal feathers are present as clinical signs, routine diagnostics should be utilized to evaluate for relevant physical disease.Paired skin biopsies (from normal and abnormal areas) are recommended to evaluate for hypersensitivity reaction.5 Treatment for identified diseases is undertaken as indicated by the diagnostic workup. In cases with possible neuropathic pain, gabapentin may have a role in management. Anti-inflammatories, primarily meloxicam, are also commonly used if generalized inflammation is diagnosed.
If psychogenic FDB is diagnosed, the environment must be evaluated and altered. Major areas of environmental focus include:8,10-12,20
Enhance behavioral repertoire
Increase complexity of environment (enrichment)
Foraging should be a specific focus of the program
Increase other opportunities to use behavior (e.g., explore, chew, tear)
Increase exercise opportunities (e.g., climb, flap, fly)
Increase positive reinforcement
Husbandry (e.g., target, come, nail trim, go to carrier)
Exercise (e.g., climb, flap, fly)
Enrichment interactions, these may need to be deliberately trained
General interactions (how the caregiver interacts outside of training sessions)
Reduce aversive interactions
Location of cage (move away from door, reduce startling)
Basic husbandry (e.g., appropriate humidity/opportunities to bath, correct nutrition, adequate rest)
It is critical to engage the caregiver fully in the change process, establish realistic goals, and develop a realistic plan in conjunction with the caregiver to help ensure implementation. Treatment programs need to be individualized for the bird and caregiver. Change should happen in a stepwise fashion that keeps the bird engaged and not overwhelmed. Caregivers should be taught what behaviors indicate an animal is uncomfortable. In addition to "fight or flight" (e.g., biting, running away), "fidget and freeze" behaviors indicate an animal is finding an interaction aversive.
A number of studies have shown that increased foraging may improve feather condition, and for many birds this should be the initial focus of enrichment intervention.Typical goals are for the animal to take 2–3 hours to identify and consume the diet. Additional enrichment opportunities should be considered. An excellent website to help caregivers is www.parrotenrichment.com.
Identifying and reducing sources of chronic stress should also be a priority. This may involve ensuring aversive interactions with caregivers are eliminated and substantially increasing the animal's choice and control but increasing positive reinforcement training and enrichment opportunities.
Primary brain dysfunction is likely common and neurophysiological medications are warranted.16-19,21 A review is available.17 Medications allow the bird to more productively engage with environmental changes and can help reduce FDB. Clinicians should be open to considering these medications to help improve the animal's general welfare. Common categories include serotonergic reuptake inhibitors (e.g., fluoxetine, paroxetine) and tricyclic antidepressants (e.g., clomipramine). Anxiolytics (e.g., valium) may have a role, either in response to acute stressors or as part of chronic management. Naltrexone has also shown some utility. As with other species, medications may take weeks to show effect and long-term planning is needed. A veterinary behaviorist can be helpful.
Even with excellent management that allows for generalized improvements in activity and time budgets, FDB may continue, though often at a reduced level. Once a behavior is part of an animal's repertoire, it does not "go away." It may not be expressed, but it can recrudesce or increase again if the management plan backtracks or in the face of environmental changes/stressors. Caregivers should be prepared for this possibility and ready to reevaluate plan implementation.
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