biology

Proventricular dilatation disease

Proventricular dilatation disease is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Proventricular dilatation disease rather than just read about it. In short: Proventricular dilatation disease (PDD) is an incurable probably viral disease of psittacine birds. It was first recognized and described in 1978 by Dr.

Key takeaways

Proventricular dilatation disease belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Proventricular dilatation disease to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Proventricular dilatation disease from memory before moving on to harder problems.

Reference excerpt

Proventricular dilatation disease (PDD) is an incurable probably viral disease of psittacine birds. It was first recognized and described in 1978 by Dr. Hannis L. Stoddard. Since the first reported cases were involving species of macaw, the condition was termed macaw wasting syndrome.

Clinical signs The clinical presentation of this disease varies with the individual as well as in severity of those symptoms. Often the symptoms include a gastrointestinal component, but many times birds with this disease will present with neurologic signs as well, or in lieu of digestive anomalies. Gastrointestinal signs may include: Regurgitation, crop impaction, poor appetite, weight loss, or passage of undigested food in the feces. Neurologic symptoms may include: Weakness, ataxia, paresis, proprioceptive deficits, head tremors, and rarely seizures. Muscle wasting and a generalized poor body condition is usually found as well. The virus can also affect the Purkinje cells of the heart, the adrenal medulla, the brain, and the spinal cord. On necropsy the affected organs appear dilated and may include the crop, proventriculus, ventriculus, and small intestine. On histopathological examination the tissues will contain a lymphoplasmacytic infiltration in the peripheral and central nervous tissue. The causative virus is believed to commonly affect the myenteric plexuses which will also lead to the presentation of atrophied smooth muscle within the affected gastrointestinal organs. It is this atrophy and loss of tone in the organs that causes the dilation and subsequent gastrointestinal symptoms which are commonly the first sign of disease for the owners.

Cause In July 2008, a team of researchers at the University of California, San Francisco was able to identify a virus that may cause PDD, which they have named avian bornavirus (ABV). A member of the Bornaviridae family, avian bornavirus was isolated in 71 percent of samples from infected birds, but in none of the healthy birds. The researchers were able to clone a full-length genome of the virus from avian tissue. Later analyses revealed that numerous distinct avian bornaviruses exist - not all of them cause PDD. Gancz et al. succeeded in inducing PDD in cockatiels by inoculation of brain tissue from avian bornavirus-positive birds while Gray et al. caused PDD in Patagonian conures by inoculation of a tissue-culture derived isolate of avian bornavirus.

Taxonomy

Diagnosis

Traditional diagnosis included radiographs. The vet may ask for a follow-up radiograph with a barium marker to collect more data on digestion to aid in confirmation of PDD. A tissue sample is a more reliable method as well but invasive yet the only definitive diagnosis with live parrots. The presence of avian bornaviruses may be detected in two ways: Testing fecal samples, cloacal swabs and blood for the presence of the virus or examining the bird's blood for ABV-specific antibodies by western blot or ELISA. All tests give a percentage of false positives and false negatives so detection of ABV or antibody against it does not mean that PDD will follow. The disease does not follow a clear path of development or transmission.

References

External links https://web.archive.org/web/20060616043500/http://www.stoppdd.org/problem/pdd_faq.html

Worked examples

Example 1 — a first encounter with Proventricular dilatation disease

Start with the simplest possible case. Write down what Proventricular dilatation disease claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Proventricular dilatation disease before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Proventricular dilatation disease ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Proventricular dilatation disease

In research: Proventricular dilatation disease appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Proventricular dilatation disease in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Proventricular dilatation disease is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bird diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Proventricular dilatation disease outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Proventricular dilatation disease in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Proventricular dilatation disease means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Proventricular dilatation disease out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Proventricular dilatation disease in simple terms?

Proventricular dilatation disease (PDD) is an incurable probably viral disease of psittacine birds. It was first recognized and described in 1978 by Dr.

Why does Proventricular dilatation disease matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Proventricular dilatation disease?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Proventricular dilatation disease.