The use of conventional radiography and computer-assisted tomography as instruments for demonstration of gross pathological lesions in the cranium and cerebrum in the crested breed of the domestic duck (Anas platyrhynchos f.dom.)

According to literature reports, the crested breed of the domestic duck (Anas platyrhynchos f. dom.) is described as a variety with high pre- and post-natal mortalities, malformations in skull and brain anatomy, and various central nervous deficiencies in affected birds. A detailed examination as to the cause and pathogenesis of these neurologic disorders has not yet been conducted, nor has an explanation concerning the inheritance of the feather crest been found. By using two non-invasive radiographic techniques, conventional radiography and computer-assisted tomography, living ducks were examined. Our studies have demonstrated that brain and skull anatomy of ducks of various breeds (Crested, Abacot Ranger, and German Pekin) can be well visualized using computer-assisted tomography. The Crested ducks investigated in this study showed abnormal fatty tissue deposits in the tentorium cerebelli, cranial malformations, and variable bone formations in the thickened hypodermis of the crest. In comparison with computer-assisted tomography, only parts of the skull changes were detected with conventional radiography; in no case could fat bodies be seen with this imaging method. An increase of the cranial capacity in the Crested ducks compared with other breeds examined (Abacot Ranger, German Pekin ducks) was found in morphometric studies carried out by computer-assisted tomography. This increase of cranial capacity in Crested ducks results from an increase of the tentorial fatty depot during craniogenesis, as an enlargement of the fat body can influence cranium growth as long as the cranial bones are not yet fused. Thus, in comparison with other phenotypically similar domesticated birds like the crested chicken, the expression of the feather crest in domestic ducks demonstrates symptomatologic differences.