The Vet's Corner - Cockatoo Feather Loss

Abstract

For the last 15 plus years, in clinical practice, we have seen countless pitiful cockatoos with mild to severe feather (and sometimes beak) abnormalities, presented by heartbroken owners for diagnosis and treatment. Because these birds and their medical affliction is so common to us we have had a tendency to assume, over the years, that most Jay people have equal familiarity with this condition. Clearly such is not the case, as evidenced by the continued large number of bewildered clients we see with these birds and more recently, by correspondence with a distraught cockatoo owner in New York who had sought the help of several veterinarians and the advice of several aviculturalists regarding this problem with no resultant satisfaction. It is for these reasons that we elected to write this article.

The Cockatoo Feather Loss Syndrome has several other symptoms. It has been caJJed "Cockatoo Rot;' "Beak Rot;' "Cockatoo Endocrine Syndrome;' "Psittacine Beak and Feather Disease Syndrome (PBFDS):' "White Cockatoo Disease;' "Cockatoo Feather Loss and Malformation Syndrome;' "Feather Maturation Syndrome;' "Cockatoo Apter ylos is}' and "Feather and/or Rhamphothecal and Ungual Keratodysgenesis'.'

Formerly, these birds were usually "foisted onto" unsuspecting bird buyers by unscrupulous or simply ignorant sellers who usually told the prospective buyer that the bird had been "caught in tar" and that the feathers "would surely grow back," or that the bird was suffering from a "dietary deficiency" which would "straighten out" with improved husbandry, or that the bird was undergoing a "severe moult." These birds would instead exhibit a chronic, progressive deterioration of beak and feathers and most would eventually succumb to a variety of diseases.

We began an intensive study of this condition about seven years ago which has included post-mortem examinations (autopsies) and clinical pathology (blood, etc.) work ups. We have not been aware of any large number of these birds that has lived more than four years, but we do know of two that have remained stable beyond this period of time. After performing over 50 autopsies, we found an extraordinarily high incidence of adrenal gland lesions with evidence of Pacheco's Disease or other causes of Inclusion Body Hepatitis in the tissues. It now appears that these lesions may have developed later in the course of the disease and were apparently secondary to the initial disease process. One of these cases was published in the Journal of The American Veterinary Medical Association.1 It is equally likely that some of the inclusion bodies noted were not associated with any disease but, instead, resulted from the storage of metabolically important materials.

Ors. D.A. Pass and R.A. Perry, Australian veterinarians practicing in New South Wales, have recently studied the disease as it occurs in the wild. 2 They have diagnosed the condition in sulfur-crested cockatoos, Major Mitchell's cockatoos, little corellas, galahs (rose-breasted cockatoos), peach-faced lovebirds, Nyassa lovebirds, hooded parrots, budgerigars, mallee ring-necked parakeets, Port Lincoln parrots, red-rumped grass parakeets, lorikeets, and western rosellas. Veterinarians in the United States have seen the disease primarily in the umbrella cockatoo, moluccan cockatoo, red-vented cockatoo, Goffin's cockatoo, and in the sulfur-crested cockatoos. Ors. Pass and Perry have seen the disease in predominantly young birds and often recognize it with the arrival of the first true feathers after the loss of their down feathers. They say that occasional cases do occur in adult birds that have not previously been noticed as having abnormal feathers. Local Australian trappers have told Dr. Pass that up to 20% of wild sulfurcrested cockatoos may be affected in some flocks. The sulfur-crested cockatoos seem to be the most commonly affected wild hosts.

Abnormal feathering (most notably incomplete maturation of new feathers) occurs in all species but changes in the beak are the most prominent in the white cockatoos and may not be as noticeable in many of the other species. We have seen severe beak changes in most of the cockatoo species we have observed in practice.

Affected birds lose down and contour feathers over most areas of the body. Ors. Pass and Perry described feather loss as roughly symmetrical with the normal plumage replaced progressively by abnormal feathers exhibiting one or more of the following characteristics: retained feather sheaths, blood retained within the shaft of the feathers, short clubbed feathers, curled and deformed feathers, stress or fault lines involving the feather vanes, and newly emerging feathers with a circumferential constriction at the base of the soft quill. This constriction of the soft feather base is what we most commonly notice in our practice and is what the client may describe as "feathers pinching off half way and breaking off.'' Lesions also occur in primary and secondary flight feathers, and major tail feathers but these may not be evident until the bird has lost many contour feathers. Essential crest feathers of sulfur-crested cockatoos are often the first to be lost. 2

Ors. Pass and Perry have observed that lesions involving the beaks of wild birds tend to start as a change in color from "gray to dark semi-gloss black'.' This is followed by progressive elongation of the upper and lower beaks, development of transverse fracture lines across the top beak and longitudinal splits in the upper and lower beaks. Uneven wear, chips, and fractures impair eating. The upper beak may become progressively undermined and chronically inflamed leading to constant tongue action and nibbling. The surface begins to bleed easily and has a tendency to become infected. Eventually these birds are unable to crack and eat seed and require a diet of soft foods. Some birds undergo toenail changes, but this isn't as common a finding. The lesions occurring in the feathers, beak, and nails are similar.

The major lesions of the Feather Loss Syndrome occur in the developing feather shaft. Investigators have found cells with cytoplasmic inclusions within the pulp and epidermal layers.2·3 Death of cells of the distal pulp and lining cells and bleeding into the distal shaft occurs, effectively choking off the developing feathers.

The exact cause of these changes is not yet known, but the presence of specific types of inflammatory cells and the presence of the aforementioned inclusion...