Proventricular dilatation disease was first described in the mid-1970s. Today, this avian disease is considered to be one of the most challenging, as not all birds show clinical signs of the disease. Different species of birds can be infected, especially parrots, regardless of sex and age and geographical distribution. Today, it is known that the etiological cause of this disease is bornavirus, and currently there are at least 8 different bornaviruses in parrots, called PaBV 1–8, divided into two different species, Psittaciform 1 orthobornavirus and Psittaciform 2 orthobornavirus (AMARASINGHE et al., 2018). Further research found that PABV-4 was associated with neurological signs, whereas PABV-2 was mainly associated with the gastrointestinal system (BOATRIGHT-HOROWITZ, 2020). Suspicion of PDD is based on the occurrence of clinical signs by the digestive and nervous systems (from weight loss and regurgitation to significant dilatation of the proventriculus, and uncoordinated movements and other signs by the nervous system) (GREGORY et al., 1994; STAEHELI et al. , 2010). Disease can be diagnosed on the basis of clinical signs, radiological examination or tissue biopsy, while the final diagnosis is made by pathoanatomical examination, finding lymphoplasmatic infiltrates. Treatment of diseased birds is not successful, but supportive therapy is advised to prolong the life of the bird. The vaccine against this disease is still not routinely used, so early detection of infected individuals and quarantine are the only mechanisms to slow the spread of this disease.