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 species, including African Greys, cockatoos, cockatiels, conures, Eclectus parrots, Amazons, and budgies.

Symptoms:

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.

Diagnosis:

- 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
• Infections:
  • 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;
  • candidiasis;
• Nutritional:
  • 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;
• Pancreatitis;
• Other systemic diseases

Treatment:

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.

Related Websites / References:

UCSF researchers identify virus behind mysterious parrot disease

Source: Kristen Bole
kbole@pubaff.ucsf.edu
415-476-2557

29 July 2008

Researchers at the University of California, San Francisco, have identified a virus behind the mysterious infectious disease that has been killing parrots and exotic birds for more than 30 years.

The team, led by UCSF professors Joseph DeRisi, PhD, and Don Ganem, MD, also has developed a diagnostic test for the virus linked to Proventricular Dilation Disease, or PDD, which will enable veterinarians worldwide to control the spread of the virus.

Results of the study will be published in “Virology Journal” and will appear online in August. The findings also will be presented in full at the August 11 annual meeting of the Association of Avian Veterinarians, in Savannah, GA.

The new virus, which the team named Avian Bornavirus (ABV), is a member of the bornavirus family, whose other members cause encephalitis in horses and livestock. Working with veterinarians on two continents, the group isolated this virus in 71 percent of the samples from infected birds, but none of the healthy individuals.

“This discovery has potentially solved a mystery that has been plaguing the avian veterinary community since the 1970s,” said DeRisi, a molecular biologist whose laboratory aided in the 2003 discovery of the virus causing Severe Acute Respiratory Syndrome, or SARS, in humans. “These results clearly reveal the existence of an avian reservoir of remarkably diverse bornaviruses that are dramatically different from anything seen in other animals.”

The discovery could have profound consequences on both domesticated parrots and in the conservation of endangered species, according to DeRisi and Ganem, both Howard Hughes Medical Investigators at UCSF. Those species include the Spix’s Macaw, currently one of the most endangered birds in the world, whose number has dwindled to roughly 100 worldwide and whose continued existence is threatened by PDD.

The research was spearheaded by Amy Kistler, a postdoctoral fellow in the DeRisi and Ganem labs. Together with veterinarians Susan Clubb, in the United States, and Ady Gancz in Israel, Kistler analyzed affected birds using UCSF’s ViroChip technology.

The ViroChip, which DeRisi and Ganem developed, is a high-throughput screening technology that uses a DNA microarray to test viral samples. The team was able to recover virus sequence from a total of 16 diseased birds from two different continents. The complete genome sequence of one isolate was captured using ultra deep sequencing.

The virus they identified is highly divergent from all previously identified members of the “Bornaviridae” family and represents the first full-length bornavirus genome ever cloned directly from avian tissue. Analysis of the Avian Bornavirus genome revealed at least five distinct varieties.

PDD is a fatal disease that causes nervous system disorders in both domesticated and wild birds in the psittacine, or parrot, family worldwide. The disease has been found in 50 different species of parrots, as well as five other orders of birds, and is widely considered to be the greatest threat to captive breeding of birds in this family, the researchers said.

The disorder often leads to the birds’ inability to swallow and digest food, with resulting wasting; many birds also suffer from neurologic symptoms such as imbalance and lack of coordination. Regardless of the clinical course the disease takes, it is often fatal.

Scientists have theorized for decades that a viral pathogen was the source of the disease, but until now, no one had been able to identify the likely culprit.

“This provides a very compelling lead in the long-standing search for a viral cause of PDD,” Ganem said. “With the development of molecular clones and diagnostic tests for ABV, we can now begin to explore both the epidemiology of the virus and how it is linked to the disease state.”

Co-authors on the paper include Amy L. Kistler, Peter Skewes-Cox, Kael Fisher, Katherine Sorber, Charles Y. Chiu and Alexander Greninger, from the Howard Hughes Medical Institute and Department of Biochemistry, Microbiology and Medicine at UCSF; Ady Gancz, from The Exotic Clinic, Herzlyia, Israel; Susan Clubb, Rainforest Clinic for Birds and Exotics, Loxahatchee, Fla.; Avishai Lublin, Sara Mechani and Yigal Farnoushi, of the Division of Avian and Fish Diseases, Kimron Veterinary Institute, bet Dagan, Israel; and Scott B. Karlene, of the Lahser Interspecies Research Foundation, Bloomfield Hills, MI.

The research was supported by funding to DeRisi and Ganem from the Howard Hughes Medical Institute and the Doris Duke Charitable Foundation. Funding for US specimen collection and veterinary care was provided by the Lahser Interspecies Research Foundation.

The DeRisi Laboratory is part of the California Institute for Quantitative Biosciences, known as QB3, a cooperative effort among private industry and more than 180 scientists at UCSF, UC Berkeley and UC Santa Cruz. The collaboration harnesses the quantitative sciences to integrate and enhance scientific understanding of biological systems at all levels, enabling scientists to tackle problems that have been previously unapproachable.

UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. For further information, please visit www.ucsf.edu.

Other Resources:

Resolution of Clinical Proventricular Dilatation Disease by Cycloogenase 2 Inhibition ... Linda Pesek - Proventricular Dilatation Syndrome ... PDD / PDS / Macaw Wasting Disease (1996) ... PDD Update (Requires Adobe Acrobat to view.) ... Proventricular Dilatation Disease (Macaw Wasting Syndrome) by Howard Voren ... Hot Spot: Proventricular Dilatation Disease (PDD) by Hannis L. Stoddard, III ... Proventricular Dilatation Disease: A Viral Epornitic ... Please, also visit: Xena's Memorial Page (Xena, was my African Grey parrot that died from PDD in 1997. She is, in fact, the reason why this entire website is in existence today)

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