To date, the lack of clinical signs, the misjudgement of possible signs and the limits of available, diagnostic tools in non-domesticated birds have made the diagnosis of respiratory disease in tropic psittacines very difficult. In accordance to this, the examinations performed prove that many diseased psittacines are diagnostically misjudged. The disease was either not noticed at all, or was only noticed in advanced stages when therapy was without success. With the use of a non-invasive diagnostic tool--computed tomography--pathological alterations in diseased gray parrots and amazons were able to be assessed based on anatomical data gained in the previous investigations on healthy birds (see part 1). In a next step results gained by CT examinations were compared to those obtained by conventional radiography. In contrast to the conventional radiography, the CT was able to demonstrate less evident alterations in earlier stages of development, thus solving problems of diagnosis which are specific for avian medicine. Especially in endangered animals, the use of such a diagnostic technique in combination with other conventional methods should be highly considered. A quick and early recognition of disease, paving the way for a successful therapy, is the fundamental prerequisite for the preservation and breeding of endangered species, making it an important, veterinary contribution to animal conservation.