Proventricular Dilation Disease in Birds or PDD

This disease was first discovered in macaws in 1978. It was originally named macaw wasting syndrome because of the high number of macaws that large number of macaws that had it. Today is it also known as psittacine wasting syndrome as it can occur in any parrot, though it is most common in macaws conures and cockatoos. Even some birds that are not psittacines, such as canaries, may be suseptible to this disease.

First, I would like to explain a specific part of a bird’s anatomy. The proventriculus is a very important part of a birds body. This is a part of the birds digestive system. It is essentially the first part of a bird’s stomach. Here, food is partially digested before heading on to the gizzard. Basically the proventriculus starts the process of digestion. The gizzard smashes up the food into a manageable size.
Proventricular Dilation Disease is caused by a virus, called the Avian Bornavirus, that attacks the proventriculus and parts of the intestine. Food therefore cannot be processed by the bird and builds up inside the bird, becoming a breeding ground for bacteria and other types of infections. Other virus’s from the Bornavirus strains cause horse and livestock disease such as encephalitis. Not all birds that are diagnosed with Proventricular Dilation Disease will harbor the Avian Bornavirus because this virus is not always the cause of the disease. There may be other virus’s and bacterium that cause the disease that have not been identified.

Symptoms of Proventricular Dilation Disease, or PDD, are pretty obvious. Weight loss is the most obvious. Your bird may also leave stools that contain undigested food particles. Abnormal enlargement or impaction of the birds crop, abdominal swelling, weakness, and vomiting are also signs. Neurological damage is common. A veterinarian will diagnose PDD most often by taking a sample from the proventriculus. If x-rays are taken, the proventriculus may be enlarged, which is also a good indicator to your veterinarian that your bird may have PDD.

How this disease spreads is not clear. Often, some birds will come down with the disease while others in direct contact remain completely healthy. One bird out of many may get PDD and leave the others without the disease. And in other cases, most birds in the same vicinity will all contract the disease, leaving only a few birds healthy.

As of now, there is no widely used treatment for PDD. Most treatments are still experimental and it is still considered a fatal disease. Birds that may have the disease or that have been diagnosed should be strictly isolated from all other birds. Some birds may live months, or perhaps much longer, with the disease and others will only live a week or two. It all probably has to do with how good the bird’s immune system is to begin with, but again, there is no real cure. There are some treatments, such as the use of anti-inflammatory drugs, that have proven to be useful, but are still being experimented with.

– Written by: Arianna Pleitez