Proventricular dilatation disease (PDD), also called avian ganglioneuritis, is a chronic viral disease of cockatiels, conures, African greys, macaws, and other parrots caused by avian bornavirus. Classic signs include passing undigested seeds in the droppings, gradual weight loss despite eating well, regurgitation, and sometimes neurological signs like tremors or weakness. PDD has no cure but careful supportive care and anti-inflammatory medication can extend comfortable life for months to years.
Last reviewed: May 2026
What Is PDD?
Proventricular dilatation disease (PDD) is a chronic, usually fatal viral disease of parrots caused by avian bornavirus (PaBV), of which several genotypes have been identified. The virus infects nerves in the GI tract, brain, and spinal cord, producing inflammation (ganglioneuritis) that disrupts normal GI motility and, in some cases, central nervous system function. Cockatiels, conures, African greys, and macaws are the most commonly affected species in pet bird populations.
Avian bornavirus is endemic in pet parrot populations worldwide, with seroprevalence of 10 to 40 percent in some surveys, yet only a fraction of infected birds ever develop clinical PDD. This makes the disease difficult to predict — many infected birds live long healthy lives and never become symptomatic, as described in the Carpenter Exotic Animal Formulary.
Recognizing PDD Signs
The classic GI presentation is undigested whole or partially digested seeds in the droppings, gradual weight loss despite a normal or even increased appetite, regurgitation, and a visibly distended crop or proventriculus. The bird appears to eat well but does not gain weight; in fact, the keel bone gradually becomes more prominent over weeks to months.
Neurological forms of PDD produce ataxia, tremors, weakness, leg paresis, head tilt, seizures, and sometimes feather plucking or self-mutilation in the affected area. Roughly 30 to 40 percent of PDD birds show some neurological involvement at presentation. Mixed GI and neurological forms are common as the disease progresses.
How Vets Diagnose It
Definitive antemortem diagnosis is challenging. Findings that support PDD include compatible clinical signs, X-rays showing a markedly dilated proventriculus and ventriculus (sometimes with retained seeds visible), and contrast radiographic studies showing delayed GI transit. Crop or proventricular biopsy showing lymphoplasmacytic ganglioneuritis is the gold standard but is invasive and risky.
PCR and serology for avian bornavirus help support diagnosis but are not definitive on their own — a positive test in a healthy bird does not predict disease development, and a negative test does not rule out PDD entirely. A multi-modal approach combining clinical signs, imaging, and bornavirus testing gives the best chance of accurate diagnosis (AAV Basic Care for Companion Birds, 2019). Comprehensive avian husbandry and isolation procedures during quarantine follow broader exotic pet care best practices (AEMV Pet Care Guides, 2024).
Treatment and Long-Term Management
There is no cure for PDD. Treatment focuses on slowing disease progression and managing symptoms. The non-steroidal anti-inflammatory drug celecoxib (a COX-2 selective inhibitor) has been used to reduce ganglionic inflammation and has shown improvement in some birds. Meloxicam is also used. Nutritional support with easily digestible foods, smaller frequent meals, and hand-feeding formula when needed maintains body condition. Probiotics and motility-supportive medications occasionally help GI signs.
Affected birds should be isolated from other parrots because the virus can spread, particularly through nasal and oral secretions and droppings. Survival after diagnosis varies widely — from weeks to years — depending on how aggressively the disease progresses and how well supportive care is maintained.
Biosecurity and Prevention
Because avian bornavirus is widespread and transmission patterns are not fully understood, prevention is difficult. New birds should be quarantined for at least 60 to 90 days before introduction to a household with other parrots. Bornavirus testing should be part of a new bird workup, with the understanding that the test is imperfect. Strict hygiene, separate food and water bowls, and limiting cross-contamination between birds reduces risk.
When to See a Vet
Not every symptom is a midnight emergency, but some warrant same-day attention and a few are true ERs. Use the lists below to sort which bucket you're in.
Call your avian vet today if:
- Whole or undigested seeds in your bird's droppings
- Gradual weight loss with a more prominent keel bone
- Recurrent regurgitation over days to weeks
- Subtle leg weakness, foot dragging, or coordination changes
- A flock mate has been diagnosed with PDD
Go to the ER immediately if:
- Sudden seizures or severe ataxia
- Inability to perch or balance
- Refusal to eat or drink for more than 12 hours
- Severe lethargy or unresponsiveness
- Vomiting that does not stop after a few hours
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Frequently Asked Questions
How much does diagnosis and treatment cost?
Initial avian vet workup with exam, bloodwork, X-rays, and bornavirus testing typically runs $400 to $900. Contrast radiographic studies add $200 to $500. Biopsy, if pursued, runs $500 to $1,500. Long-term care with anti-inflammatory medications, special diet, and periodic rechecks averages $50 to $200 per month for the duration of life.
Can PDD be cured?
No — PDD is a chronic disease with no cure. Treatment focuses on managing symptoms, slowing progression, and maintaining quality of life. Some birds live for years with supportive care; others decline more rapidly. Outcomes vary widely between individual birds.
Is PDD contagious to my other birds?
Yes — avian bornavirus can spread between parrots, primarily through close contact with respiratory secretions, droppings, and feather dust. Affected birds should be isolated from healthy flockmates. Strict hygiene, separate food and water, and avoiding cross-contamination help reduce spread. However, many infected birds never develop clinical disease, complicating decisions about how to manage exposed birds.
Can I get PDD from my parrot?
No — avian bornavirus has not been shown to cause disease in humans. There is no documented case of human illness from this virus. Standard good hygiene practices (handwashing after handling birds, not sharing food or kissing the bird) are appropriate, but PDD is not a zoonotic concern.
How do I tell PDD apart from a simple crop infection?
Crop infections like candidiasis or sour crop typically present with sudden onset, often after antibiotic use or stress, and respond to antifungal or other targeted treatment within days. PDD is chronic and progressive, with weight loss over weeks despite normal appetite, undigested seeds in droppings, and sometimes neurological signs. An avian vet can usually distinguish them with exam, crop swab, and imaging.
Still Not Sure if Your Bird Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of your bird's droppings or any weight change, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.