Proventricular Dilatation Disease (PDD) aka Neuropathic Gastric Dilatation or Macaw Wasting Disease
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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.
- PDD—A Deadly Disease by Jeannine Miesle, MA AFA FOA, CA Levels 1 & 2, PIJAC CAS Member, AFA, AAV
- Suggestions for Daily Living with PDD by Jeannine Miesle, MA AFA FOA, CA Levels 1 & 2, PIJAC CAS Member, AFA, AAV
- UCSF researchers identify virus behind mysterious parrot disease by Kristen Bole
Typical symptoms include constant or intermittent regurgitation, chronic bacterial or fungal crop infections, pendulous crops, weight loss, passage of whole intact seeds in droppings, incoordination, depression or sudden death.
Concomitant central nervous system signs may include ataxia, abnormal head movements, seizures, and proprioceptive or motor deficits.
These signs, unfortunately, are not specific for this disease. Other conditions, such as lead poisoning, bacterial and fungal infections, foreign bodies and obstructions, can mimic this disease.
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.
At necropsy, emaciation, pectoral muscle atrophy, and dilation of the gastrointestinal tract, including the proventriculus, are observed.
This being said, many diseases mimic PDD and each of these must be carefully ruled out. These include:
- 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
Possible Treatment (to be discussed with vet):
Heavy Metal Toxicity: Several birds that were diagnosed with PDD were treated for metal toxicity and fully recovered. Since PDD is so difficult to diagnose and is often misdiagnosed, treatment for heavy metal toxicity should be considered. Treatment is inexpensive and birds often recover quite quickly.
Anti-inflammatory: Some success has been achieved by using anti-inflammatory agents with significant activity in the CNS, peripheral nervous system, and gastrointestinal tract. The drug Celecoxib, specifically, significantly improved the functional status of PDD-affected birds, and appears to be safe and well tolerated in these species. Treatment duration was for a period of 6 to 12 weeks with the decision to cease medication based upon the return to normal body weight, condition, and diet.
Supportive care focused on improving gastrointestinal transit (fluids, apple pectin), providing nutritional support with easily digested hand-feeding formulas and appropriate therapy to eliminate bacterial (Clostridial) and fungal enteric infections.
Holistic treatment options include olive leaf extract because of its excellent anti-viral properties. Other beneficial herbs are St. John's Wort and Echinacea. These can be made into a tea or mixed in with nut butters.
Long-term prognosis is grave for birds that actually have this disease, with the majority of birds succumbing after a period of progressive debilitation and wasting. However, many birds are being misdiagnosed, so providing supportive care and naturally strengthening the bird's immune system may help cure those that have been misdiagnosed. Even those that do have PDD can live many years if they are provided excellent care. Some stories of recovery have also been circulated.
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Information contained on this website is provided as general reference only. For application to specific circumstances, professional advice should be sought.
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