Avian Bornavirus and Proventricular Dilatation Disease
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Limit spread while seeking adviceSeparate affected animals when practical and obtain veterinary guidance on contacts, cleaning and normal mixing.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Parrot bornavirus infection can trigger avian ganglioneuritis, historically called proventricular dilatation disease. Immune-mediated inflammation damages nerves supplying the gastrointestinal tract and sometimes the central and peripheral nervous systems. Infection is commoner than clinical disease: many infected parrots remain healthy, while birds that develop inflammatory nerve damage may decline progressively.
Loss of gastrointestinal nerve function slows motility and dilates the proventriculus. Birds can eat eagerly yet lose weight, regurgitate, pass whole seeds or develop crop and intestinal stasis. Secondary bacterial or fungal overgrowth may follow. Neurological disease causes tremors, ataxia, weakness, seizures, abnormal vision or self-injury. Myocarditis is another recognised manifestation. Macaws, conures and African greys are often represented, but nearly all parrot species are susceptible.
Whole seed in droppings reflects failed digestion or transit and can also occur with Macrorhabdus, obstruction and other digestive disease. Bornavirus infection does not invariably progress to ganglioneuritis; clinical disease develops when inflammation damages enough enteric or central nerves to disrupt function. This distinction explains why exposed birds within one collection can have very different outcomes.
There is no antiviral cure. Anti-inflammatory and supportive treatment may improve function for months or years, but progressive ganglioneuritis can be fatal. Transmission appears inefficient in some settings and remains incompletely understood; faecal and urinary contamination is still a concern. Healthy infected birds should not be assumed to have inevitable PDD. Digestive and neurological injury can occur separately or together, fluctuate over months and progress at different rates, so quality of life depends on maintained weight, safe swallowing, mobility and control of secondary complications. Inflammation may affect scattered nerve regions rather than the entire tract uniformly, which explains why regurgitation, delayed transit, blindness, tremor or self-injury can dominate in different birds.
Screening & Early Detection
Record serial gram weight, appetite, regurgitation, crop emptying and whether intact seed appears in droppings. Neurological examination assesses vision, coordination, strength and proprioception. Radiographs, contrast studies or fluoroscopy evaluate proventricular size and transit, while blood tests identify malnutrition and secondary infection.
PCR is commonly performed on cloacal swabs or fresh faeces, ideally repeated because shedding is intermittent. Serology documents immune response and can complement PCR. Neither test alone proves PDD. Crop, proventricular or ventricular biopsy may demonstrate characteristic ganglioneuritis, but sampling sensitivity and surgical risk require specialist discussion.
Macrorhabdus, obstruction, heavy-metal toxicity and other neurological or wasting diseases are investigated. New and positive birds are housed separately while results are clarified. Home monitoring uses weight and dropping photographs, not visual appetite alone. Rapid weight loss, persistent regurgitation, seizure or inability to perch requires urgent care. Serial negative tests provide stronger evidence than one sample but cannot guarantee lifetime freedom from infection. Because shedding can be intermittent, repeated PCR testing of choanal and cloacal swabs may be needed. Antibody tests demonstrate immune response but cannot alone diagnose PDD. Imaging assesses gastrointestinal dilation, and crop or proventricular biopsy may reveal characteristic ganglioneuritis, though a negative biopsy does not completely exclude it.
Treatment & Management
Feed an easily digested nutritionally complete diet in small frequent meals and monitor daily weight and crop function. Fluids, warmth and assisted nutrition support birds that cannot maintain intake, while severe stasis or obstruction must be addressed before force feeding. Prokinetic medication may improve transit in selected cases. Culture-directed antimicrobials or antifungals treat secondary overgrowth.
Veterinary anti-inflammatory therapy, often an NSAID, may reduce ganglionic inflammation and improve signs, but kidney and gastrointestinal effects require monitoring. Anticonvulsants or neuropathic-pain medication address neurological manifestations. No antiviral has proven able to clear bornavirus, and treatment response does not confirm diagnosis.
Reduce reproductive and social stress, provide quiet predictable housing and separate infected birds from negative birds with dedicated cleaning equipment. Recheck weight, chemistry, motility and neurological function. Medication is adjusted to the lowest effective regimen, and relapse is expected in some birds. A healthy positive bird may need separation and surveillance without clinical drugs. Prognosis is guarded once severe wasting, recurrent aspiration, seizures or inability to eat develops; humane euthanasia is appropriate when nutrition, comfort or safe mobility cannot be maintained. There is no proven cure for the underlying infection. Highly digestible food, smaller frequent meals and assisted feeding can support birds with poor motility, while anti-inflammatory therapy is selected cautiously and monitored. Housing should reduce falls or seizures, and infected birds should not be introduced into unexposed breeding groups.
Breeds or species affected
Adelaide Rosella
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Bourke's Parrot
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Budgerigar
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Cockatiel
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Eastern Rosella
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Elegant Parrot
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Galah
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Hooded Parrot
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Little Corella
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Long-billed Corella
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Musk Lorikeet
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Pale-headed Rosella
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Port Lincoln Parrot
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Princess Parrot
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Rainbow Lorikeet
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Red-capped Parrot
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Red-collared Lorikeet
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Red-rumped Parrot
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Scaly-breasted Lorikeet
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Scarlet-chested Parrot
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Sulphur-crested Cockatoo
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Twenty-eight Parrot
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Western Corella
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Western Rosella
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Yellow Rosella
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Indian Ringneck Parakeet
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Alexandrine Parakeet
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Peach-faced Lovebird
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Fischer's Lovebird
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Sun Conure
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Jenday Conure
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