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Proventricular Dilatation Disease
Dr. Branson W. Ritchie, DVM, Ph.D, Dipl. ABVP - Avian, Dipl. ECAMS
(Bird Paradise June 10, 2006)
Proventricular Dilatation Disease|
- First reported in the late 1970s
- Epornities in US, Canada, and Europe
- Over 50 species of Psittacines susceptible
PDD Not just for Psittacines Anymore
- Free-ranging Geese
- Free-ranging and Captive Spoonbills
- Honey Creeper
- Passing undigested or poorly digested foods
- Ataxia, seizures, paresis
- Contrast Radiographs for GI Dilatation and Slowed Emptying Time
- Its not PDD until your pathologist gives you a histologic diagnosis of
- Crop or Proventricular Biopsy for Antemortem Diagnosis
- Take an eraser sized biopsy that includes blood vessels
Proventricular Dilatation Disease
- Bacterial Gastroenteritis
- Fungal Gastroenteritis
- Any Intra or Extraluminal mass
ex: Leather impaction
80 n m Enveloped Particles Recovered from Naturally & Experimentally Infected Birds
Suspect viral nucleic acid sequence bound to cells adjacent to inflammed areas of the brain!
Virus-like particles inside cell from area that was probe positive!
Assay performed well in research birds, but was problematic in field trials!
2001, established 2 breeding pairs of cockatiels
- in pair A the cock was PDD positive
- in pair B the hen was PDD positive
Data derived from natural and experimental PDD transmission
Concerning with respect to the number of birds that are sub-clinically infected,
and presumably shedding the PDD agent!
- Raised by Donor Aviculturist
- Male hatched in 96
- Female hatched in 97
- Normal clutches from 1999 to mid 2001
Severity of Histologic Lesions MAY NOT Correlate with Disease Progression or Prognosis
Cock minimal focal LP Ganglionitis in 2001
Died in January, 2004
Hen Severe multifocal LP Ganglionitis in 2001
Still stable and reproducing
PAIR A (PDD positive cock)
Produced 5 fertile eggs
- 2 dead in shell and 3 hatched
- Attempted experimental transmission in chicks
- Inoculated chicks intraorally, intranasally, intraocularly, and intramuscularly
with tissue homogenates from PDD positive birds
Approximately 10 weeks after first inoculation
One chick was depressed, developed progressive ataxia and was euthanized
- bird died from bacterial septicemia
Thought provoking findings?
- Chick was PDD negative even though it was raised by a PDD cock!
- PDD reported in a 28 day old chick
Yet this cockatiel was negative at ~ 80 days old
- In Our Adult Transmission Studies, we have documented incubation period of
10 days to 3 months
Findings support our theory that many infected birds remain
sub-clinical, develop an immune response and clear the virus!
Used 3.5mm magnifying loops to make skin incision over left lateral crop with 20 g needle
5-0 PDS Suture passed at cranial edge of biopsy site
consistent vascular plexus was site of each biopsy
Out of 12 chicks
- 1 chick died from sepsis PDD negative despite being produced and raised by PDD + cock
- 3 chicks died from PDD 2 naturally-acquired and 1 experimentally-infected
- 3 chicks clinically normal and PDD +
- 1 chick clinically normal with Igluvitis
- 1 chick clinically diseased that is crop biopsy neg.
- 1 chick with weight loss that is PDD +
Review of Important Clinical Data
- Confirmed disease transmission in control setting
- Transmission and disease progression unpredictable even with intimate/prolonged contact
- Gastric Motility (Radiography) may not correlate with histologic changes in crop,
particularly during sub-clinical phase of disease
- Histologic lesions in the crop may be segmental and multiple step sections
maybe be necessary to confirm a diagnosis
"Isolate, dont euthanize exposed sub-clinical birds"
- Birds with GI form can survive for years when provided easily digested diets
- Isolate positive birds
- Birds improve when treated with Interferon, Antibiotics, Antifungals & Antiinflammatories
- Several antivirals improve condition experimentally, but danger of resistance
given that mammals may be susceptible
Would you like more information on how to donate to Dr. Richie's PDD research?
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