The PDD Problem

The term Proventricular Dilatation Disease (PDD for short) is used to describe an inflammatory response characterized by the accumulation of lymphocytes and plasma cells in the central and peripheral nervous systems, especially the nerves that supply the muscles in the proventriculus and other digestive organs including crop, ventriculus and small intestine. Central nervous system signs associated with PDD, which may occur in addition to or independent of gastrointestinal signs, may include ataxia, abnormal head movements, seizures and proprioceptive or motor deficits. The most common clinical signs of PDD include depression, weight loss (with or without decreased appetite), constant or intermittent regurgitation, and/or passage of undigested food in the feces indicating a malabsorptive or maldigestive disorder.

PDD was first discussed in the late 1970's in birds imported into the United States and Germany. Subsequently, a PDD epornitic has been occurring in psittacine birds in North America and Europe, probably as a result of the widespread importation and shipment of birds to satisfy the demands of the pet trade. There is no reference to spontaneous disease in free-ranging psittacine birds; however, they should be considered psittacine or non-psittacine birds susceptible. Given the severe nature of PDD and its potential to affect a wide range of bird species, the importation of psittacine birds or their eggs into any region with indigenous Psittaciformes must be considered extremely risky.

EDRG, University of Georgia, College of Veterinary Medicine, excerpted from the
AAV Proceedings, August 2004, Epizootiology of Proventricular Dilatation Disease in Breeding Cockatiels