Electron microscopic search for retrovirus particles in spontaneous tumors of the parakeet

Survey of the Clinical, Cytological, and Histopathological Features Associated with Neoplasms in Captive Avian Species in Melbourne, Australia

Over a 3.5-year period, tissue samples from 141 companion and aviary birds with clinically suspected, naturally occurring solid neoplasms were collected via surgical biopsy (n = 53) or at necropsy examination (n = 88) from a population of birds presenting to an avian veterinary clinic in Melbourne, Australia. Neoplastic processes were identified in 73.7% (n = 104) of samples, with 83.7% (n = 87) being interpreted as malignant neoplasia and 16.3% (n = 17) being interpreted as benign neoplasia. The overall estimated prevalence of neoplasia in the study population (n = 5125) was 2.45% (95% confidence interval, 2-2.97%). The gastrointestinal and reproductive tracts were the most commonly affected systems. The most common presenting signs were nonspecific and included lethargy, coelomic distension, and inappetence. In 59 cases, fine-needle aspirates (FNAs) and impression smears were also obtained and evaluated cytologically. The accuracy of cytology for detecting neoplasia in birds and for determining whether a neoplastic process was benign or malignant was assessed by using histopathology as the "gold standard." There was complete agreement between the cytological and histopathological diagnoses in 72.8% (43/59) of cases. Cytology correctly identified 87.5% of these cases (35/40) as malignant neoplasms and 55.6% (5/9) as benign processes. There was no significant difference between the use of cytology and histopathology for the detection of malignant neoplasia in birds (P = 0.185). The accuracies of FNAs and impression smears for examining avian tumors were also compared. Overall, the best cell preservation was obtained by performing impression smears from tissues, with 62.2% (n = 28) returning high cellularity for cytological examination, compared to 53.8% (n = 14) when samples were obtained by FNA. This study provides an overview of the types and prevalence of neoplasms in a captive bird population from Australia, correlates physical examination findings with tumor types, and provides evidence that cytology is a reliable preliminary diagnostic tool for detecting neoplasia in birds.

Palliative Radiation Therapy for Treatment of Cutaneous T-cell Lymphoma in a Double Yellow-headed Amazon Parrot (Amazona oratrix)

A 17-year-old captive female double yellow-headed Amazon parrot (Amazona oratrix) was presented to the Kansas State University Zoological Medicine Service (Manhattan, KS, USA) for a 2-month history of a left sided facial swelling. On examination, a red, raised mass was noted on the left side of the face. A whole-body computed tomography scan of the bird was performed to assess the extent of the mass and evaluate the patient for obvious evidence of disseminated disease. No systemic involvement was detected, and the swelling was localized to the cutaneous and subcutaneous tissues overlying the left rhamphotheca. Two punch biopsies were collected, and histopathology was consistent with cutaneous lymphoma, with strong positive CD3 staining congruous with a T-cell origin. Because of a lack of evidence for disseminated disease, the authors elected to pursue localized radiation therapy, and a single fraction of 8 Gray was administered. The swelling had resolved by the time of the recheck examination 4 weeks post-radiation therapy, and the patient remained clinically normal 52 weeks after radiation therapy.

Cutaneous Hemangiosarcoma in a Pacific Parrotlet (Forpus coelestis)

A 2-month-old Pacific parrotlet (Forpus coelestis) was presented for assessment following a traumatic injury to the right wing that resulted in persistent swelling and inflammation. Six weeks postinjury the bird underwent surgical resection of a large hemorrhagic cavitated mass that had formed at the site of the original injury and a second, smaller mass on the body in direct contact with the wing mass. Histopathology of the wing mass confirmed a diagnosis of hemangiosarcoma. While commonly diagnosed in domestic species, hemangiosarcoma is uncommonly reported in avian species. To the authors' knowledge, this is the first report of hemangiosarcoma in a Pacific parrotlet and describes the development of hemangiosarcoma in a psittacine bird following trauma-induced inflammation.

Osteoma in a blue-fronted Amazon parrot (Amazona aestiva)

Osteoma is an uncommon bone formation documented in avian species and other animals. A blue-fronted Amazon parrot (Amazona aestiva) with clinical respiratory symptoms was examined because of a hard mass present on the left nostril. Radiographs suggested a bone tumor, and the mass was surgically excised. Histopathologic examination revealed features of an osteoma. To our knowledge, this is the first description of an osteoma in a blue-fronted Amazon parrot. Osteoma should be considered as a differential diagnosis in birds with respiratory distress and swelling of the nostril.

Treatment of nonepitheliotropic cutaneous B-cell lymphoma in an umbrella cockatoo (Cacatua alba)

A 3.5-year-old umbrella cockatoo (Cacatua alba) was presented because of the development of widely disseminated subcutaneous nodules. The diagnostic work-up included a complete blood count, plasma biochemical analysis, and whole body radiographs. Biopsy samples of the skin lesions were submitted for histopathologic evaluation, bacterial culture and sensitivity testing, immunohistochemistry staining, and acid-fast staining. The diagnosis was nonepitheliotropic cutaneous B-cell lymphoma with a leukemic blood picture. The bird was treated with a chemotherapeutic regimen consisting of vincristine and chlorambucil for 17 weeks. During treatment, the complete blood count was monitored every 1-3 weeks, and the plasma biochemical analysis was monitored every 3-4 weeks. The bird was in partial remission on week 9. On week 17, the bird became acutely ill and was fluffed, depressed, anorectic, and anemic. The chemotherapeutic regimen was discontinued. At this time, the bird had a consistent lymphocytosis but no neoplastic lymphocytes were seen in the general circulation. At week 29 the bird was in complete remission and remains in complete remission 8 years after chemotherapy was discontinued.

Clinical approach to renal neoplasia in budgerigars (Melopsittacus undulatus)

Renal neoplasia in budgerigars (Melopsittacus undulatus) is seen regularly in general practice and is of interest to many practicing veterinary surgeons. This review article provides an overview of the current knowledge and the most recent reports in avian literature regarding renal tumours in budgerigars, with the emphasis on clinical diagnosis and treatment. The high prevalence of renal neoplasia in budgerigar is discussed, with notes on the most commonly diagnosed tumours, possibility of metastases, sex and age predisposition. The possibility of ultrasonography and radiography in the diagnosis of this pathological condition are compared as well as the possible role of blood and urine analyses. Two studies are described, both of which investigate the possible involvement of a retrovirus as the aetiological agent.

Tumors of pet birds

Neoplastic diseases are becoming more than a postmortem diagnosis due to the increasing knowledge base and improving quality of avian medicine. The expectation for better health care demands a diagnosis, prognosis, and therapy options. However, the published information regarding prognosis and therapy of specific neoplasms remains limited in avian medicine. With each case report or study that provides this information, there is an improvement in the level of care we can offer our companion avian species. This review will cover some basic information about specific tumor types and will reference the more recent reports in the avian literature. It is not intended to be all encompassing.

Viruses as environmental carcinogens: an agricultural perspective

Under natural circumstances tumor viruses can be considered as risk factors which in themselves are neither necessary nor sufficient to produce cancer; they may do so, however, if provided with suitable genetic and environmental conditions. It follows that a reduction in amount of virus or other environmental cofactors may prevent the associated tumors. In this paper we will consider four major families of viruses associated with cancer in animals and man, and will highlight the exogenous cofactors and related preventive measures. We will mention those agricultural practices that have resulted in significant economic loss from virus induced cancer in farm and domestic animals and will summarize some of the occupational hazards from environmental agents other than tumor viruses.