PDD is a progressive disease often fatal, that occurs in several parrot species but a common susceptibility of all parrots is suspected. It also may occur in non psittacine bird like, gooses, hawks, doves tucans and flamingos. The ill birds develop gastrointestinal or central nervous system signs. These presentation can be occur like a combination of both or alone. The clinical signs are caused by histological nervous lesions, characterized by a non suppurative encephalomyelitis and/or perineural lymphoplasmacytic infiltrates around peripheral nerves. The intramural neural plexa of digestive tract were constanctly involved. The diagnosis is characterized by inconsistent clinical laboratory findings. A presumptive diagnosis of PDD is often based on anamnestic information, contrast radiographs, fluoroscopy in PDD suspect birds. Until now the only specific and reliable method used for the diagnosis is the crop biopsy. The presence of characteristic histological perineural infiltrates are strongly suggestive of the disease and necessary for a definitive diagnosis. Until now the etiology and the pathogenesis are unclear, even if, many Authors suppose the potential role of unclear virus as the causative agent of PDD. The different aspects of this disease show a lot of analogies with the human Guillain Barre' syndrome, so we have focalised the our study to clarify the pathogenesis. To do this, we investigated if the PDD can be an autoimmune disease and if a possible presence of the blood antiganglioside antibodies can be the starter of this autoimmune pathological mechanism, like was observed in more than 50% of the GBS's cases.