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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 1970’s
  • 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
  • Toucans
  • Finches/Canaries
  • Honey Creeper

Symptoms

  • Emaciation
  • Regurgitation
  • Passing undigested or poorly digested foods
  • Ataxia, seizures, paresis



Diagnostic Aids

  • Contrast Radiographs for GI Dilatation and Slowed Emptying Time



Proventricular Dilatation

  • It’s not PDD until your pathologist gives you a histologic diagnosis of
    Lymphoplasmacytic Ganglioneuritis



Diagnostic Aids

  • Crop or Proventricular Biopsy for Antemortem Diagnosis
  • Take an eraser sized biopsy that includes blood vessels



Lymphoplasmacytic Ganglionitis
IS
diagnostic

NOT
Lymphoplasmacytic Enteritis
Lymphoplasmacytic Ingluvitis




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
  • Intriguing
  • Informative
Concerning with respect to the number of birds that are sub-clinically infected,
and presumably shedding the PDD agent!



PAIR A

  • 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, don’t euthanize exposed sub-clinical birds"



    Prevent Transmission

    • Fresh air and sunlight


    Treatment

    • 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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