Developmental Malformations in Avian Species. Manifestations of Unknown or Genetic Etiology-A Review

The anomalies which occur during the development of the avian organisms result in structural and functional abnormalities. In the present review, the majority of surveyed reports on developmental malformations are related to wild birds and secondarily to poultry birds. Regarding their etiology, spontaneous and genetic aberrations were surveyed. The great part of malformations refers to the skeletal system. Among them, the most frequently occurring types were beak deformities, absent, supernumerary or deformed limbs. Embryonic conjoined duplications were also recorded. Anomalies of structure, number and coloration of feather were highlighted. Abnormalities of the heart and ocular malformations were compiled. Also, malformations of the gastrointestinal as well as of the uro-genital system were collected. The malformations which were briefly described constitute a database which could be a useful tool for the further study of embryology, experimental toxicology and teratology of animals.