Teresa L. Lightfoot D.V.M., Diplomate ABVP - Avian
The phrase "feather plucking" covers the range from mild over-preening through self-mutilation. The avian practitioner will see many degrees and patterns of feather destructive behavior. There is no doubt that feather plucking is one of the leading reasons that captive pet birds are brought to the veterinarian. It is also one of the most challenging and frustrating syndromes seen in practice.
Feather plucking seldom has a single etiology. A partial analogy from companion animal medicine may help to understand and correctly approach the feather plucking bird. Chronic lick granulomas of dogs are a good example. These too are usually frustrating, with multiple contributory factors. There may be medical reason(s) for the initial production of the lesion (an abrasion, atopy, etc.) but behavioral factors are often involved in the exacerbation and chronicity of the condition. However, before we label either of these conditions as primarily behavioral, it is prudent to thoroughly explore potential medical problems. Also, as with canine lick granulomas, extensive client communication concerning feather plucking in birds at the onset will help the client to realize that the odds are NOT in the favor of a simple cure, nor necessarily ANY cure. Our goal is to improve the health of the bird, and to reduce or eliminate the plucking behavior.
The possible etiologies for feather plucking will be listed and briefly discussed under the appropriate categories.
1) Endoparasitism (especially Giardiasis in cockatiels) and occasionally tapeworms or roundworms.
2) Ectoparasites (although rare, they will occur just as soon as you cease to add them to your differential). The red mite (Dermanyssus gallinae) may be the most common of rare ectoparasites involved in actual feather plucking.
3) Hepatic disease. Regardless of the nature of the hepatopathy, pruritus associated with liver dysfunction may cause plucking.
4) Coelomic cavity granuloma or mass.
5) Neoplasia (this will tend to be a localized plucking area associated with an underlying mass).
6) Folliculitis/dermatitis. These conditions can be primary, or secondary to excessive plucking and/or mutilation. Bacteria, virus, fungus or yeast may be involved.
7) Allergies (though difficult to confirm, a change in environment when allergens are suspected may lead to a decrease in plucking and a tentative diagnosis by elimination).
8) Endocrine abnormalities, the most likely being hypothyroidism. Hypothyroidism is a much over-diagnosed condition, due in part to the lack of established normal values for avian thyroid levels and the absence of a reliable TSH response test. Nevertheless, some obese birds that demonstrate a lack of weight loss following a rigid diet, accompanied by poor quality feathers and infrequent molts may be thyroid deficient. The plucking exhibited by these birds is often an attempt to rid themselves of old, damaged feathers.
9) Heavy metal toxicity - notably zinc. Barbering and feather plucking from zinc ingestion has been reported. Many of these cases will not have radiographic evidence of heavy metal, and require a blood zinc analysis for diagnosis.
This may be a more common category of factors contributing to feather plucking than the classic medical conditions listed above. Basic seed and table food diets often create multiple nutritional deficiencies. These deficiencies cause abnormal skin and feather development resulting in plucking behavior, as well as a myriad of other medical problems that may occur later in life. The dyes and preservatives that are added to seeds and most pelleted diets may be detrimental to birds. This seems to be most common in species such as African Grays, Eclectus parrots, and some cockatoos. The relatively low humidity in most households also has a drying effect on the skin. Being deprived of natural sunlight, fresh air, humidity and the normal light/dark cycle has negative physiologic and psychologic effects on birds.
Many times, although treatment of medical and environmental factors may reduce the severity of feather plucking, a strong behavioral component is also involved. It is common to treat for the above-mentioned problems and note an initial improvement, only to have a relapse of the condition at a later date. The psychological factors that can lead to plucking are numerous but it is important to remember that all of these are displaced behavior in response to some psychologic stressor. The analogy of fingernail biting in people is often apt and allows the client to relate to the problem. It also explains the persistence of plucking even when the apparent causes have been remedied. A person may begin to bite their fingernails while undergoing a very stressful time in their lives. Once the stress has been relieved, the habit may still remain. It is noteworthy that feather plucking does NOT occur in the wild. Wild birds are occupied with finding food, maintaining their position in the flock, seeking out and finding a mate, avoiding predators, and breeding and raising young. Therefore, often the best-kept birds with all their apparent needs met, will be the pure behavioral pluckers. The owners find comfort in this explanation, since they often feel that somehow they have been negligent, or their bird wouldn't be bald! Psychological conditions that may cause feather plucking in birds can vary, and opposite situations can cause plucking in one bird, and the cessation of plucking in another. Over-stimulation (i.e. a house full of active children) may cause plucking in a nervous bird. Another bird that was plucking from boredom may feel both stimulated and slightly threatened by the presence of this increased activity in the home, and stop plucking in order to pay attention to the environment. This capitalizes on the bird's basic instinct to guard itself against potential predators. Birds that are reaching sexual maturity may begin to pluck as an outlet for their increased energy and agitation. Owners of these birds will often report that their birds are showing more cage territoriality, more aggression toward one or more family members, and possible sexual behavior toward a perceived human mate or inanimate objects.
A thorough understanding of the environment of the bird and the associated behavioral changes that have accompanied the onset of plucking, will allow the veterinarian to make the appropriate suggestions for environmental manipulation to change these conditions.
When the anamnesis points to a dominance and/or sexual cause of plucking, the veterinarian and owner may elect to combine environmental manipulation with either hormonal or psychotropic medications. Neither of these categories of drugs tend to produce long term positive results, and side effects are possible from several of these medications. The following is a partial list of these drugs, their indications, contraindications, and potential usefulness.
1) Diazepam: This medication seems to be of limited usefulness. Most birds require a dosage that causes sedation in order to deter feather plucking. Some owners have reported that their birds fall off their perch when they attempt to sleep while on diazepam. Oral dosages of 2.5 - 4.0 mg/kg have been reported, to be repeated as needed.
2) Haloperidol: Anecdotal reports exist of this drug having reasonable efficacy , notably in cockatoos. Serious side effects, including anorexia, hepatic dysfunction, and CNS signs, have been reported. Suggested doses are 0.15 mg/kg q 24 hours for larger birds, and 0.2 mg/kg q 12 hours for smaller species.
3) Prozac (fluoxetine): Reports of the usefulness of this medication have varied widely. A dose of 2 mg/kg q 12 hours is reported empirically. The mediation has met with little success in this author's practice, however, it may be that, as in humans, an initial loading period is necessary for the manifestation of therapeutic effects.
4) Elavil (amitriptyline): Anecdotal reports find this drug to be of some usefulness. As with Prozac in people, the maximum effect is not reached for several weeks. Barring side effects, it may be worth a more prolonged course of this mediation to determine its usefulness. Dosages published are 1 - 2 mg/kg q 12-24 hrs.
1) Medroxyprogesterone acetate (Depo-Provera). This drug was used for many years as a deterrent to sexual behavior, including feather plucking. Unfortunately the side effects ranged from weight gain, polyuria and polydipsia (PU/PD), and lethargy, to more severe conditions such as hepatopathy, diabetes mellitus, and death. The response of each bird to a given dose varies, and this medication is not recommended for use in routine feather plucking. When the risks of this medication are determined to be acceptable to the veterinarian and the owner, the dosage range is between 5-25 mg/kg intramuscularly. The lowest possible effective dose should be used, and all efforts to modify the birds behavior should be made in conjunction with this therapy.
2) Chorionic gonadotropin (hCG) This drug has met with moderate success, particularly in female birds. The predominately LH activity of hCG stimulates the production and release of progesterone in females. When successful, the female bird tends to pluck much less, be less aggressive, and not to experience side effects such as weight gain, PU/PD, lethargy, or the more severe reactions as are listed for Depo-Provera. In male birds, testosterone as well as progesterone are produced in response to LH, and the success rate is much lower. An exception seems to be Eclectus males, where the response to hCG has been equal to that of females of other species. This correlates with the lower levels of testosterone, and higher levels of progesterone, found normally in the limited number of Eclectus males that have been tested. Dosage protocols are totally empirical at this point in time. A commonly used regimen is the administration of 500-1,000 units/kg intramuscularly. Generally, if no response is seen within three days, the dose is repeated. If no response is noted after this second injection, in this author's experience, repeated or increased dosages are unlikely to be effective. The injection if successful in reducing plucking, will initially need to be repeated after four to six weeks. The major drawback of this medication is that with repeated usage, the interval between injections must be decreased. After three years of treatment with hCG, some birds need injections as frequently as every 10 days. Although repeated serum chemistries have shown no adverse effects, this frequency is inconvenient for the owner, and long term use of hCG at this dose and interval has not been studied. The most likely reason for this phenomenon of increased resistance is the development of antibodies to hCG.
3) GnRh Agonist, Depo-Lupron12 This functions to increase in release of LH and FSH. Its efficacy is probably also based on the bird's response to LH and subsequent negative feedback on the production of sex hormones. Dosage recommendations vary, with 100 - 500 ug/kg I.M. being within the current empirical dosage range. (See the description of the pharmokinetics of this drug in the following section on chronic egg-laying)
In addition to the traditional medical therapies, acupuncture has been utilized with some reported success. In this author's experience, the birds that have been referred for acupuncture and have responded favorably were usually of the genus Cacatua. Other avian veterinarians have reported this as well.8
The use of Omega fatty acids as a dietary supplement has been used to treat feather plucking with some success. Whether this is due to the anti-prostaglandin affect or a true fatty acid deficiency is not certain. The canine Derm CapsR can be punctured with a needle and the contents added by the drop to the food.
An ideal medical treatment is not likely to be found for feather plucking in captive birds. Manipulation of the environment ensuring quality nutrition, and psychological adaptations suited to the species and temperament of the bird offer the best hope for reducing this syndrome. The maintenance of a non-domestic species in a domesticated environment requires that we use all available resources to ensure the highest quality of life for our avian patients.
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