Proventricular Dilation Disease – PDD in Birds

Let’s say that lately you’ve been noticing that your bird isn’t feeling well. It’s lethargic, dull, and has ruffled feathers. Then you start noticing that it’s not getting better. In fact you’ve realized that even though it’s eating more, it is still losing weight. Maybe its poop smells, perhaps it has begun to vomit and maybe there’s undigested food in its poop. A bird that is not feeling well looks lethargic and dull. There could be plenty of reasons why a bird is not feeling well. It could be eating the wrong food, have parasites or an infection, or it could be afflicted with one of many different problems. It could have Proventricular Dilation Disease.
Proventricular Dilation Disease (PDD) is a disease that can affect either the digestive system or the neurological system. Before explaining PDD, we will give a short summary of the unique digestive system of birds, because in this disease it is common to have the whole digestive tract affected. Food goes in through the beak, where it is shelled and broken down into smaller pieces. Next it hits the crop, which is a sac in the neck that is used to store and soften food. Then the food moves onto the proventriculus (‘pro’ means before, so it’s the sac before the ventriculus). In the proventriculus the food is stored and it starts being digested. After the proventriculus, the food enters the ventriculus. The ventricles is a big grinding sac. It functions like our molars, to grind food, but it also functions like our stomach, to digest food. From there the food enters the intestines for nutrient absorption.
As mentioned before, PDD can affect the digestive system or the neurological system. Sometimes it affects both. The reason that it can affect both systems is because it targets neurons. Most of the time it only affects the neurons of the digestive system, which results in the digestive tract losing ‘tone’ and dilating. When the digestive tract dilates it cannot perform its function of breaking down food and absorbing nutrients properly. This why birds with PDD often lose weight, even if they are eating properly. Less commonly, PDD can affect the neurological system instead of the digestive system. These birds can have a variety of signs, but generally will have awkward and uncoordinated movements.
It may seem that PDD is a complicated disease. PDD can have different levels of severity. Some birds will die quickly from PDD. But PDD is like an iceberg; for the number of PDD-affected birds that are seen, there are many birds that have PDD but never show it. Some birds can have PDD but will show no signs and will not be harmed by the disease. These birds pose a threat to other birds because they can pass PDD on to healthy birds.
PDD is very infectious and is found worldwide. It is most commonly seen in Cockatoos, African Grays, and Macaws. It is old enough to be well-known, but it is also still fairly new; PDD has only been recognized for around 50 years. Because it is still fairly new, it is still not completely understood. Research suggests that PDD is probably caused by a virus and is spread through contamination with feces. There is no set treatment for PDD, although there are a few experimental drugs being used that do a good job of controlling the disease in birds that are not severely affected by the disease.
So why should you care about PDD? You should care because there is no cure for it yet. You should care because your bird can get it from a seemingly healthy bird, that has PDD but doesn’t show the signs. You need to be aware of the fact that PDD is fairly common. There is no need to panic about PDD, but every bird owner should be aware that it is out there, and that putting multiple birds together increases the risk of transmitting PDD.
How can you help protect your bird? The best thing that you can do for a sick bird, in any situation, is to take it to the veterinarian right away. The sooner you detect a problem, the more you can do to stop it. PDD is a disease that can affect the digestive or neurological systems of your bird. It may never cause any problems in some birds, while causing fatal problems in other birds. It is highly infectious so PDD is a disease that you should be aware of.