Some Disease Conditions Of Aviary Birds Based On Pathologic And Clinical Findings At The University Of Zimbabwe Veterinary Hospital And Pathology Laboratory From 1986- 2004
B Dzoma, E Mulenga-Muradzikwa
aviary birds, clinical, disease, pathologic, prevalence
B Dzoma, E Mulenga-Muradzikwa. Some Disease Conditions Of Aviary Birds Based On Pathologic And Clinical Findings At The University Of Zimbabwe Veterinary Hospital And Pathology Laboratory From 1986- 2004. The Internet Journal of Veterinary Medicine. 2007 Volume 4 Number 1.
A review of 880 aviary bird case files, including pathology, biopsy, and clinical findings was conducted at the University of Zimbabwe Veterinary Pathology Laboratory and Hospital for the period 1986- 2004. The ages of the birds ranged from hatchling to 40 years old. Ninety-two percent of these were psittacines while the remainder were passerines. Among the psittacines, the Lovebird and the African Grey parrot had the greatest prevalence rates of 46% and 17% respectively. The passerines included the threatened Lady Gouldian finch, the canary and the mynah. Infections accounted for the greatest cause of mortality at 64%. Some causes of mortality had a species biased distribution, with the lovebird succumbing mostly to the psittacine beak and feather disease (PBFD) virus and aspergillosis. However, the majority of problems transcended species barriers. Of the zoonotic agents, only Salmonella, Mycobacterium and Chlamydophia psittaci were noted. Biosecurity measures need to be reinforced in order to curb the spread of infectious agents.
Aviary birds are quite commonly used as pets because of their beauty, colour and ability to mimic talking. A variety of infectious (Andersen and Vanrompay, 2000; Black et al., 1997; Clavijo et al., 2000; Grimes et al., 1997; Hoop et al., 1996; Sanchez-Cordon et al., 2002; Shihmanter et al., 1998) and non-infectious (Duff, 1997; Gibbons et al., 2000; Harrison, 1998; Koutsos
The objectives of this study were to show the prevalent disease conditions of aviary birds in Zimbabwe and highlight their zoonotic infections, based on pathologic and clinical findings at a national referral diagnostic facility.
A total of 880 aviary bird case files, including pathology, biopsy, and clinical findings, were reviewed at the University of Zimbabwe Veterinary Pathology Laboratory and Hospital for the period 1986- 2004. The centre is a national referral diagnostic facility, and the period covered began with the time of inception of the facility. Standard and routine pathologic and clinical diagnostic methods were employed at the institution in line with acceptable standards for veterinary diagnosis. The files used included standardized clinical and pathology record forms that guaranteed standardization of records, and ensured an internal agreement on standard nomenclature over the study period.
Data were collected and summarized for parameters that included history, clinical signs, gross postmortem lesions, histopathology, microbiology, and parasitology. A summary of the species of aviary birds, and their most prevalent pathologic and clinical findings was subsequently compiled. Period prevalence was compiled by pooling together the number of birds for the period under study.
A total of 880 case files were reviewed, and involved mainly the lovebird (
Among the psittacines, the lovebird and the African Grey parrots had the greatest prevalence rates of 46% and 17% respectively. The passerines (8%) included the threatened Lady Goulidan finch (
Of the infectious agents, the psittacine beak and feather disease (PBFD) virus occurred most frequently, affecting mainly the lovebird and African Grey parrot. Other viruses (suspected herpes/adenovirus, poxvirus), bacteria
The tumours included a carcinoma in a 25 year old African Grey parrot, and fibrosarcomas and lymphosarcoma in African Grey parrots and budgerigars. The carcinoma in the African Grey parrot grossly presented as a white to medium-brown, well circumscribed but deeply attached subcutaneous tumour extending from the external auditory meatus to the submandibular area. The centre was necrotic and had a rich blood supply. Histopathologic examination revealed nests and cords of pleomorphic epithelial cells. The cells were large, bizarre shaped, multinucleated, and with mitotic figures. Attempted stratification was seen in some areas, with clear spaces in between the cells as seen in the stratum spinosum. Desmoplasia was pronounced in the background. However, since it was a biopsy specimen, it was not possible to determine the exact origin of the tumour, or to give a specific diagnosis other than that of carcinoma. Some findings had a species biased distribution, with the lovebirds and African Grey parrots succumbing mostly to the PBFD virus and aspergillosis (Table 2). However, the majority of problems transcended species barriers. Of the zoonotic agents 109 (4%), only
The diagnostic techniques used during clinical and pathologic investigations generally proved satisfactory for the diagnosis of various conditions. The bird species submitted generally represented the variety of aviary birds noted in different parts of the world. However, it was not possible from this study to verify aspects such as species popularity. The species that were submitted included endangered species, namely the Cape parrot of South African origin, which has a pending CITES Appendix 1 listing, and the Lady Gouldian finch. Not all parrot species were specifically named, and for purposes of this study, a group known as ‘other parrots' was established.
Infectious agents were the most commonly encountered finding (64%) among the birds and included viruses, bacteria, and fungi. The isolated bacteria (
The viral infections included circovirus, poxvirus and suspected herpes/adenoviruses. Psittacine circovirus is the causative agent of PBFD, which is generally considered a disease of the psittacine species (Albertyn et al., 2004). In this study, only lovebirds and a few African Greys were affected. PBFD has been associated with varying clinical and mortality patterns in different lovebird species in Zimbabwe (Kock et al., 1993). The virus is transmitted horizontally primarily through viral shedding in the feather dander (and possibly vertically). Psittacine circovirus can cause feather pulpitis, multifocal necrosis of feather and follicular epithelium, exudative folliculitis, feather loss, beak and claw lesions, and an immunocompromise that opens the way to opportunistic infections (Roy et al., 2003). Ante-mortem diagnosis is possible through histopathologic examination of plucked feathers, feather follicle biopsies or biopsies of affected palatine beak epithelium, looking for the typical lesions and globular basophilic intracytoplasmic viral inclusions in macrophages and epithelial cells. In some countries, the detection of circoviral DNA in a blood sample, using DNA probe technology, is available for ante-mortem diagnosis, and is often more definitive and sensitive in detecting infected individuals than feather histopathology (Roy et al., 2003). Circovirus inclusions are also commonly found in the bursa of juvenile psittacines dying acutely of overwhelming opportunistic infections, often before feather or beak lesions are noted clinically.
Only three zoonotic agents (
Internal parasitism accounted for 6% of the cases, and mainly involved gastrointestinal roundworms and tapeworms in a variety of psittacines. It should be remembered that some cestodes, such as
Non-infectious diagnoses included tumours (5%), nutritional problems (4%), traumatic injuries, cloacal impactions, and pneumoconiosis. The tumours in this study included carcinomas, fibrosarcomas and lymphosarcoma in African Grey parrots and budgerigars. In the literature, tumours have been recorded in aviary birds, and have included gastrointestinal adenocarcinoma and cholangiocarcinoma in a peach-fronted conure (
The nutritional problems (4%) recorded included vitamin A and calcium deficiencies in the African Grey parrot. Vitamin A deficiency can be recognized by frequent respiratory infections, scaliness on the feet and beak, and poor plumage (Schoemaker et al., 1999). Nutritional problems are common in pet birds because of an all-seed diet (Harrison, 1998; Koutsos et al., 2001; Koutsos et al., 2003
Other non-infectious findings included traumatic injuries, cloacal impactions and pneumoconiosis. Pneumoconiosis in birds' lungs can be related to housing in dusty, enclosed locations, and are for the most part incidental lesions at post-mortem. Reports of clinically relevant pneumoconiosis are also available, and include that in an eagle, diagnosed on ante-mortem lung biopsy, which was presumably due to exposure to train engine exhaust in a zoological park (Joseph, 1996). The risk factors and specific causes of the pneumoconiosis in this report were not determined.
The lovebird and African Grey parrot were the most commonly encountered species, while infectious agents, particularly the PBFD virus, were the most commonly diagnosed problems among the birds. The occurrence of zoonotic infections like
We thank Mr P. Mlambo for assistance in data organization, and all Clinicians and Pathologists at the University of Zimbabwe Veterinary Teaching Hospital and Pathology Laboratory for their invaluable input.