Bird - Proventricular Dilatation Disease (PDD)

General information

First recognised in the early 1970s, proventricular dilatation disease was originally called Macaw Wasting Disease, as the disease caused a gradual wasting of macaws. Since that time, the disease has affected many species of pet birds.

What is proventricular dilatation syndrome (PDS)?

PDS is not the same as PDD!

It describes the enlargement and reduced/slowing of stomach movements and/or emptying. It has a number of causes (infections, toxicities) as well as PDD.

PDD is a condition affecting the nerves supplying the gastrointestinal tract (guts) of birds, mainly the proventriculus or true stomach. Sometimes the intestine may be affected. On occasion the central nervous system (brain/spine) can be affected and skin signs may develop from involvement of nerves to the skin..

What causes the condition?

Microscopically, the affected nerves are inflamed with an infiltration of certain types of white blood cells.While a number of agents may cause this type of reaction, an avian bornavirus (ABV) has been strongly associated with these cases and is now regarded as the cause of PDD..

What are the signs of birds affected with PDD?

The old name, Macaw wasting disease, aptly describes affected birds. Birds have a lack of appetite, show regurgitation, may pass undigested seeds in their faeces, and exhibit weight loss. Neurologic signs such as seizures or tremors may also occur. Some birds will pick feathers and even damage their skin. No one sign is definitive for the condition; however, proventricular dilatation should be suspected in birds with chronic unexplained regurgitation, weight loss, and any time undigested foods are seen in the droppings.

How is the condition diagnosed?

Clinical signs may suggest PDD. Radiographs (x-rays), including a barium series may also strongly suggest the condition by showing enlargement or delayed emptying of the stomach or gut. The only definitive way to diagnose PDD is with a biopsy of the proventriculus or crop. Crop biopsy is normally performed as it is much safer than proventricular biopsy. However, it is at best only 65% accurate – if the biopsy is positive then it is confirmed. However, a negative biopsy does not rule out the disease.

Can the disease be treated?

Supportive care, including treatment of secondary diseases and force feeding as needed, can be given, but the condition is ultimately fatal. Recently use of a non-steroidal anti-inflammatory drug, celecoxib has been shown to slow progress of disease in some birds.