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Contrast studies are commonly performed to evaluate the gastrointestinal tract. With ever increasing knowledge of Proventricular Dilation Disease (PDD) in psittacines, and its association with avian bornavirus, radiographic assessment of the proventriculus is used as a diagnostic and screening tool for PDD (Bond and others, 1993, Boutette and others 2004, Clubb and others 2006). Contrast radiography is carried out following crop tube administration of a radiopaque solution. The resulting radiographic series gives information on gastrointestinal tract morphology with approximation of transit time by evaluating contrast medium progression. However, each single exposure requires fixed positioning, and stress associated with repeated handling and restraint can directly affect motility, thus distorting results (Tully and others 2000). Use of anaesthesia is advisable in minimising stress and improving positioning, but this risks regurgitation of contrast medium on induction with associated aspiration pneumonia. Anaesthesia itself has effects on intestinal contractility (Tully and others 2000). Gaseous anaesthetic induction can also lead to aerophagia and gaseous dilation of the gastrointestinal tract, complicating film interpretation and potentially leading to false positive identification of proventricular dilation (McMillan 1999). There is significant variation of gastrointestinal transit time reported between avian species, and also between individuals with factors such as diet, food availability, health, stress, medications administered and age cited as factors (Garcia Martinez and others 2007).
Fluoroscopy has been proposed as an alternative to radiography, avoiding some of the complicating factors and offering additional advantages (Ritchie and others 2004, Harcourt-Brown 2005). The real-time images produced allow assessment of gastrointestinal tract …