PROVENTRICULAR DILITATION DISEASE
Also known as Macaw Wasting Syndrome, neuropathic gastric dilatation, proventricular dilatation syndrome, myenteric ganglioneuritis, psittacine wasting syndrome, proventricular hypertrophy & infiltrative splanchnic neuropathy and more recently, lymphoplasmacytic ganglioneuritis & encephalomyelitis, PDD is a disease of suspected viral etiology that affects the nerves supplying the gastrointestional tract and central nervous system. Adults are more commonly affected (3:1, adult:juvenile) with equal distribution among the sexes. The incubation is thought to be anywhere from 1 week to 3 months. The suspected causative agent is an enveloped virus measuring 80nm, and via inoculation into healthy birds, has resulted in the clinical picture observed in birds diagnosed with PDD. The disease can assume an acute or chronic course. Birds can die within 5 days upon demonstration of clinical disease or assume a chronic course lasting months to years.
The major clinical signs are depression, weight loss, regurgitation and passage of undigested food in the feces. Birds may also be presented with neurological signs such as ataxia, seizures and motor deficits. Diagnosis is based upon clinical signs suggestive of PDD, crop biopsy (tissue must include a major blood vessel;~70% success rate), radiographic findings of proventricular dilatation. A DNA probe is being researched. It must be remembered that birds may exhibit gastrointestional and/or neurologic disease, thus negative radiographic findings does not preclude a diagnosis of PDD. This disease may occur in any flock despite excellent hygiene, quarantine procedures, and preclusion of new birds to the collection. A flock may lose a few birds acutely and not have another problem for years. Hand reared psittacines in single bird households with no exposure to other birds have succumbed to the disease years later. This random occurrence in established aviaries or single bird households may suggest that PDD is not caused by an infectious agent, it is a slow progressive disease, has a long incubation period, can be transmitted by mechanical or biological vectors, or can occur following activation of a latent infection. It appears that a carrier state may also exist as evidenced by persistent infections in neonates from the same breeding pairs.
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