Proventricular Dilatation Disease (PDD) in Parrots

What Is Proventricular Dilatation Disease?

Proventricular Dilatation Disease (PDD), also called Macaw Wasting Syndrome or Avian Ganglioneuritis, is caused by Avian Bornavirus (ABV). The virus damages the nervous system that controls gut motility. The proventriculus (the glandular stomach in birds) and other gastrointestinal segments dilate and become dysfunctional. Affected birds cannot properly digest food — undigested seeds appear in the droppings. The disease also causes neurological signs in some birds. There is no cure, but management can significantly extend quality of life.

Signs of PDD

Undigested seeds or whole food in droppings (despite appearing to eat normally)
Progressive weight loss despite good appetite
Crop distension with food that doesn't move (crop stasis)
Vomiting or regurgitation of partly digested food
Neurological signs: ataxia, seizures, abnormal head movements (in some birds)
Regurgitation immediately after eating

First 3 Steps to Take at Home

Check droppings for undigested food: The classic sign is whole or barely digested seed pieces in the dropping. In a healthy bird on seed, the seed coat is digested away. If you see whole seeds in the dropping of a bird that appears to be eating normally, this is highly significant.
Weigh the bird regularly: PDD causes progressive weight loss that owners often attribute to age or stress. Weekly weights reveal the gradual decline that visual assessment misses until it's quite advanced.
Contact an avian vet for testing: Diagnosis requires crop biopsy (most reliable), proventricular radiograph (characteristic dilatation), and ABV serology. The combination of tests is needed as no single test is 100% reliable.

When to Go to the Vet Immediately

Bird with undigested food in droppings combined with weight loss
Neurological symptoms (seizures, head tremors, inability to perch) in any bird
Crop that remains full and doesn't empty over 24 hours

Follow-Up Care Checklist

Transition to highly digestible foods: pellets ground fine, soft cooked foods, easily digestible vegetables
Anti-inflammatory medication (celecoxib or meloxicam) is used to reduce neurological inflammation — this is not a cure but can slow progression
Isolate from other birds — ABV can spread between birds
Regular weight monitoring to track disease progression

Track PDD Progression with TailRounds

Weekly weights, dropping observations, and feeding behavior logs in the TailRounds Daily Log are essential for monitoring PDD birds.

Book a Vet Appointment

Suspected PDD requires specialized diagnostic testing. Book at Happy Paws with our avian-experienced exotic team for comprehensive evaluation.

Summary for Your Clinic Visit

Bring a fresh dropping sample, describe the dropping changes, tell your vet the weight history, the current diet, and any neurological symptoms observed.