CAGE'N BIRD

PROVENTRICULAR DILATATION SYNDROME

Christopher R. Gregory, D.V.M., Kenneth S. Latimer, D.V.M., PhD.,

Frank D. Niagro, PhD., Raymond P. Campagnoli, MS,

Cheryl B. Greenacre, D.V.M., Branson W. Ritchie, D.V.M., PhD.

Psittacine Disease Research Group

University of Georgia

College of Veterinary Medicine

Athens, Ga. 30602

Summary: Involvement of central and peripheral nervous tissues with lymphoplasmacytic inflammatory infiltrates is characteristic of proventricular dilatation syndrome (PDS). An etiologic agent has not been found for PDS, although recent findings are increasing the likelihood that the syndrome is caused by a virus. Suspicion of PDS is based upon historical information, clinical signs and radiographic evidence of proventricular enlargement or dysfunction. Definitive diagnosis of PDS requires the demonstration of characteristic lymphoplasmacytic infiltrates within nervous tissue. The syndrome cannot be diagnosed by clinical abnormalites or necropsy findings. Microscopic examination of the ventriculus, proventriculus, crop or brain of affected birds is currently the only way to confirm the syndrome.

A recently recognized infectious agent is killing companion, aviary, and free-ranging birds throughout the world. At present, no birds or aviaries are known to be protected. This dreaded affliction is called Proventricular Dilatation Disease (PDD).

What Species are susceptible to PDD?

In the order Psittaciformes, PDD has been reported in more than 50 species, including the families Cacatuidae (Cockatoos and Cockatiels) and Psittacidae (Lovebirds, Macaws, Parakeets, Parrots, Amazon Parrots, Conures). Pacific, South American and Afro-Asian species have been described with characteristic lesions. Suggestive lesions also have been reported in free-ranging Canada Geese (Branta canadensis, Order Anseriformes), and Spoonbills, Toucans and Weavers. Other non-psittacine birds also may prove to be susceptible to this disease as improved tests are developed to accurately diagnose affected individuals. Clinical reports suggest that adults are more commonly affected than neonates.

When was PDD first recognized and what synonyms have been used?

Proventricular Dilatation Disease has been recognized since the late 1970's. Initially, the disease seemed to be limited to macaws. This fact, in conjunction with an unknown cause, gave rise to the terms macaw wasting or fading syndrome, wasting macaw syndrome, and gastric distension of macaws. As it became apparent that the disease occurred in psittacines other than macaws, a more general terminology was used to describe the disease, including psittacine wasting syndrome, proventricular hypertrophy, or proventricular dilatation syndrome. Various terminology also has been used to describe the pathological features of this disease, including neuropathic gastric dilatation, myenteric ganglioneuritis, proventricular and ventricular myositis, psittacine encephalomyelitis and infiltrative splanchnic neuropathy.

What are the signs of PDD?

The most common clinical signs of PDD include depression, weight loss, constant or intermittent regurgitation, and/or passage of undigested food in the feces indicating a malabsorptive or maldigestive disorder. Proventricular impaction, muscle atrophy, abdominal enlargement, lethargy, weakness, polyuria, diarrhea, scant feces or hypotension also have been reported in some birds. When the central nervous system is involved, signs may include ataxia, abnormal head movements or seizures. Some affected birds may develop central nervous system signs in the absence of gastrointestinal abnormalities.

How is PDD diagnosed?

A presumptive diagnosis of PDD is based on historical information, clinical signs, and radiographic evidence of proventricular dilatation or dysfunction. Confirming that a living bird has PDD is difficult. Biopsy of the ventriculus or proventriculus can be used to diagnose the disease. However, obtaining a biopsy sample from these organs is invasive and dangerous. In some birds, biopsy of the crop can be used to diagnose the disease. At necropsy, emaciation, pectoral muscle atrophy, and dilatation of the esophagus, proventriculus, ventriculus, or small intestine are observed commonly. The proventriculus may appear thin-walled and friable. Microbial infections, parasitism, gastrointestinal obstructions, neoplasms, trauma, malassimilation disorders, toxin ingestion or malnutrition may cause similar changes and also must be considered. A definitive diagnosis is often made after death when microscopic examination of the tissues reveals the characteristic lymphoplasmacytic inflammatory infiltrates in central and peripheral nervous tissues.

What causes PDD?

The etiologic agent of PDD remains unconfirmed, although recent research conducted by the Psittacine Disease Research Group at the University of Georgia implicates an infectious agent. The disease apparently has subacute, acute and chronic stages; however, the majority of diseased birds die within several months to a year after developing clinical signs. Interestingly, disease does not develop in all exposed birds, which suggests that some birds have an innate resistance, develop a protective immune response, lack factors that are required for inducing the disease, possess factors which prevent development of the disease, or develop a carrier state. The fact that some exposed birds remain normal is good news for the avicultural community. This suggest that continued research efforts could provide effective control measures to prevent disease.

What can be done for birds with PDD?

Unfortunately, all birds with confirmed PDD have died. Until further information is available about the virus that is causing this disease, preventative measures such as quarantine of new birds, avoidance of direct or indirect contact between isolated groups of psittacine birds and appropriate hygiene are the only available methods to reduce exposure.

PDD Summary:

Proventricular Dilatation Disease is a deadly infection that can kill many species of parrots and other birds. There is no effective treatment. Recent findings confirmed that this disease is infectious. Suspicion of PDD is based upon historical information, clinical signs and radiographic evidence of proventricular enlargement or dysfunction. Definitive diagnosis of PDD requires the microscopic demonstration of characteristic lymphoplasmacytic infiltrates within nervous tissue. The disease cannot be diagnosed by clinical abnormalities or gross necropsy findings.Microscopic examination of the ventriculus, proventriculus, crop or brain of affected birds is currently the only way to confirm the disease.

The Board of the IAS is proposing a concerted effort to fund the research necessary to stop PDD before it claims more companion birds or spreads to our native, free-ranging birds.

Through support provided by professional aviculturists and companion bird enthusiasts, the Psittacine Disease Research Group at the University of Georgia has made great progress in improving the health of our feathered friends. Psittacine Beak and Feather Disease (PBFD), which once killed thousands of birds each year can now be prevented by use of a diagnostic test. When the DNA probe test for PBFD virus became available in 1992, the impact of this disease was significantly reduced and aviculturists were able to reduce exposure to this virus by establishing tested, virus-free flocks.

Polyomavirus, the leading cause of death in young parrots, can now be prevented with an effective and safe vaccine. A list of veterinarians in your area that are using the vaccine can be obtained by calling the vaccine's manufacturer (913-894-0230). Additionally, the Psittacine Disease Research Group is working with researchers at Louisiana State University to determine if a newly developed test can be used to establish flocks of birds that are free of Chlamydia psittaci (the cause of Psittacosis).

Dr. Ritchie and the Psittacine Disease Research Group would like to continue work on PDD, provided the necessary funds are available. Funding donated by the avicultural community will be augmented by support from the state to allow this group to continue their vital research.

Links to Articles

Overview of the PDD Research Plan:

A. Confirmation of causative organism:

Currently, the Psittacine Disease Research Group has recovered a virus they suspect is causing PDD. This virus must be identified and characterized.

B. Development of a management technique:

After the causative agent is characterized, an accurate testing procedure must be developed to identify infected birds. A vaccine to prevent infections will need to be developed if the virus cannot be managed by testing alone.

We estimate the required avicultural contribution to insure PDD is quickly resolved will be $300,000 over a three year period.

To raise these funds, the International Aviculturists Society appeals to the entire avicultural community as well as individual companion bird owners. IAS is a non-profit 501(c)(3) corporation with NO SALARIED POSITIONS. All donations to the PDD project are directed donations for PDD research, and IAS will absorb any overhead expense in administering this project. The Psittacine Disease Research Group will keep donors informed of their progress through semiannual reports.

Donor Catagories:

Each donor will receive published recognition and appreciation awards for annual donations.

Guarantor ($5,000 and above) - engraved plaque

Benefactor ($2,500 - 4,999) - engraved plaque

Patron ($1,000 - 2,499) - engraved paperweight

Sponsor ($500 - $999) - engraved paperweight

Supporter ($100-499) - certificate

Donor ( $25 - 99) - tie tac pin

******************************************************************************

___________________________________________

Mailing Address: Street:__________________________________________________________

__________________________________________________________

City: _________________________________ State: ________ Zip: _____________

Country: _____________________________________

Phone: ______________________________

Donation:$___________________________

If Credit Card, Please circle Visa MC Card #___________________________

Expiration Date: ______________

Signature: _______________________________________

Please forward or fax to:

PDD Fund

International Aviculturists Society

P. O. Box 280383

Memphis, TN 38168

Fax (901) 872-4149 (waking hours please CST)

Thank you. Your contribution is appreciated!