Proventricular Dilatation Disease (PDD) or Macaw Wasting Disease
PDD is a very devastating, fatal disease affecting not only macaws, but has been seen in many other parrot species, including African Greys, cockatoos, cockatiels, conures, Eclectus parrots, Amazons, and budgies. There also are reports that suggest that birds that are very distantly related to parrots can be infected, such as spoonbills, toucans, peregrine falcons, Canadian goose, weavers, and possibly ostriches.
Antemortem diagnosis of Proventricular Dilatation can be difficult. Suspicion of this disease is based upon history and physical examination. A complete workup should be performed, which includes a CBC, blood chemistry, bacterial and fungal cultures and sensitivities, and a chlamydia test. Survey and contrast X-rays may demonstrate a dilated proventriculus (glandular stomach) and delayed passage of barium from the gastrointestinal tract. These findings further support a tentative diagnosis but are not conclusive. A definitive diagnosis is based upon a biopsy of the crop, ventriculous (gizzard) or proventriculous, demonstrating characteristic histopathologic changes. The characteristic lesions may not be uniformly distributed throughout the affected organ, so multiple biopsies are necessary.
- Heavy metal toxicity (i.e., lead) which can be accompanied by signs of esophageal or proventricular dilatation, intestinal ileus (paralysis), impaction, abnormal droppings as well as neurological signs;
- Impaction or signs of maldigestion due to disorders of the lining of the ventriculus (known as the koilin layer) that can be caused by heavy metal toxicity, parasitic / fungal infection, candidiasis or internal Papillomatosis;
- Ingestion of foreign material (metals,plastics, grit, feathers, nesting material) that can cause symptoms of proventriculus and/or ventriculus obstruction or impaction
- bacterial, mycobacterial; fungal or viral infections, such as Avian Viral Serositis, Adenovirus and Paramyxovirus III
- parasitic infections
- gastric nematode infections capable of causing weight loss, anemia, and signs of gastric impaction (anorexia, regurgitation, scant feces);
- protozoa infections including trichomoniasis and cryptosporidiosis;
- Vitamin D Toxicosis and the accompanying mineralization of digestive organs;
- vitamin e/selenium deficiency;
- Dysplastic Koilin causes proventricular obstruction and/or tulceration and perforation of the Ventriculus (gizzard)
- Gastric tumors or other masses causing obstruction or the digestive tract;
- Other systemic diseases
Source: Avian Web