Psittacine Proventricular Dilatation Syndrome (PPDS)

posted: 05/15/12
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Psittacine Proventricular Dilatation Syndrome (PPDS) is known by many names, including Macaw Wasting Disease and Neuropathic Gastric Dilatation. Thought to be viral in origin, PPDS is contagious and often devastating, with mortality approaching 100 percent.

What is PPDS?

PPDS is a disease of the digestive tract of birds. To understand this disease, one needs to know more about the digestive system in birds. The proventriculus is the glandular stomach, directly connected to the esophagus and the place where gastric juices are secreted. From there, food is passed to the ventriculus, which is the muscular stomach or what most people know as the gizzard. In PPDS, the nerves that supply the muscles of the proventriculus, ventriculus, and other parts of the digestive system are affected. As a result, the food does not pass through the organs as it should. Birds with PPDS are unable to absorb nutrients due to the destruction of gastric motility and secondary improper digestion.

Which birds are susceptible to PPDS?

Young or old, imported or domestic, and male or female birds are equally at risk for PPDS. For unknown reasons, a higher incidence of PPDS is seen in African Grey Parrots and Blue and Gold Macaws, although any of the psittacines are susceptible to this disease. Some non-psittacine birds, such as toucans, canaries, and weaver finches have been suspected of having this disease.

What are the signs of PPDS?

A bird with PPDS will be depressed, regurgitate, pass whole seeds in the feces, and often show progressive central nervous system signs. These can include ataxia, the inability to perch, head tremors, and paralysis. Seizures may actually be the first presenting sign before any signals of gastric upset are evident. Eventually, due to lack of nutrition because of the body's inability to effectively digest and assimilate food, affected birds loose the bulk of their pectoral muscle mass and the keel becomes very prominent, hence the term "wasting" disease. PPDS can also masquerade as lead or zinc poisoning, foreign body ingestion, and a few other maladies, so correct diagnosis is important.

How is PPDS diagnosed?

Diagnosis is generally based on history, signs, and evidence of an abnormal proventriculus. Contrast radiography using barium will most often show a greatly enlarged proventriculus, and often, a fairly normal ventriculus. A biopsy (removal and examination of tissue) is necessary to confirm the diagnosis.

What is the treatment and prognosis?

The prognosis is poor. While the use of steroidal treatment is controversial, it is sometimes used. PPDS generally does not respond therapeutically. When the signs are not severe, a soft, easily digested diet such as steamed vegetables, soft fruits, and a commercially prepared, extruded (cooked) diet (as opposed to pelleted) is sometimes helpful in digestion and making the bird more comfortable. The bird should be kept in a stress-free environment, and may need to be treated with antibiotics to avoid secondary bacterial infections.

A bird with PPDS should be placed in strict isolation, and have no direct or indirect contact with other birds.

Often, birds do not show any signs of illness until they are, in fact, very sick. In birds, a "wait and see" attitude can take a turn for the worse very quickly. Any time you suspect illness in your bird, consult your avian veterinarian.

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