Dipartimento di Sanita` Pubblica Veterinaria, Sezione di Patologia Generale e Anatomia Patologica, Faculty of Veterinary Medicine, University of Messina, Viale Annunziata, Messina, Italy A Case of Conjoined Cephalopagus Twinning in an Ostrich (Struthio camelus) G. Mazzullo 1 *, G. Montalbano 2 , A. Augello 3 , A. Germana ` 2 and B. Macrı ` 1 Addresses of authors: 1 Dipartimento di Sanita` Pubblica Veterinaria, Sez. Patologia Generale e Anatomia Patologica, Facolta` di Medicina Veterinaria, Universita` di Messina, Viale Annunziata, 98168 Messina; 2 Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali, Sez. Morfologia, Facolta` di Medicina Veterinaria, Universita` di Messina, Viale Annunziata, 98168 Messina; 3 AUSL 3, Piazza Levantino, 1, 95047 Paterno` (Catania), Italy; *Corresponding author: Tel. +39 090 350 3705; fax: + 39 090 350 3951; e-mail: gmazzull@unime.it With 1 figure Received July 2005; accepted for publication July 2006 Summary Conjoined twinnings have been reported in most domestic animal species and in some avian species. Cases of conjoined twins have not been reported in the ostrich so far. A hybrid Blue neck · African black male ostrich conjoined twinning was born at the end of artificial egg incubation and died spontaneously 24 h after the hatching. It was frozen and sent to the Unit of Veterinary Pathology of the University of Messina for gross examination. The most important gross findings involved the external body and most of the internal organs. On the basis of the duplication, the conjoined twins were classified as a cephalopagus. Radiological features included: development of one head containing a single brain, two spinal cords, deviated vertebral columnae with fusion of the two first cervical vertebrae. In one twin, the synsacrum was absent as well as portions of the vertebral column. Grossly, both twins showed two upper and lower limbs each. The gastro-enteric apparatuses of the twins were not completely developed and fused at different levels. One liver and one heart localized in the centre of the conjoined twins were observed. The authors conclude that the possible causes of the malfor- mation could be related to a genetic factor. Introduction Congenital defects are structural or functional abnormalities present at birth. They can affect an isolated portion of a body system, the complete system or parts of several systems (Dennis and Leipold, 1979). Among them, conjoined twins, on the basis of an exclusively morphological concept, are generated by the union of two more or less developed organisms, or by a body partially duplicated to the almost total formation of two individuals. Different terms have been proposed for the classification of such anomalies, on the basis of the parts or regions involved in the duplication or the fusion, and also according to certain geometrical plans (Schwalbe, 1907; Duhamel, 1966; Guttma- cher and Nichols, 1967; Leipold et al., 1972). Conjoined twins are classified, according to the most prominent site of connection, in craniopagus, cephalopagus, thoracopagus, omphalopagus, pygopagus, ischiopagus and rachipagus (Duhamel, 1966; Kingston et al., 2001). The causes of conjoined twins have still not been clearly elucidated. Defects of blastogenesis have been proposed as responsible for abnormal development of conjoined twins, where the midline and mesoderm formation represent an important step in blastogenesis and in the beginning of gastrulation (Singh et al., 2003). In avian species, cases of incomplete duplications or spontaneous malformations have been described in the hen (Gericke, 1950; Hoffman, 1968) and in avian embryos (Romanoff and Romanoff, 1972; cited by Riddell, 1975). Furthermore, Sittman et al. (1971) described body duplica- tions (anterior, posterior, partial or incomplete twins) with a similar frequency in quail, chicken and turkey. Available literature data about ostrich malformations report the occurrence of supranumerary legs (Horbanczuk et al., 2004) and limb deformities with a highest incidence at the beginning of the breeding season and lowest towards the end, when the outside temperature was warmer (Mushi et al., 1999). To the best of our knowledge, cases of conjoined twins have not been reported in ostriches to date. Materials and Methods A hybrid Blue neck · African black male ostrich conjoined twinning, born at the end of artificial egg incubation, was found by the owner in his farm located in Sortino (Syracuse, Sicily, Italy). The animals were reared in a half-wild state. The eggs were collected immediately after being laid and put in a separate plastic bag to avoid contamination. During the artificial incubation, the temperature was around 32°C until the end of incubation, when the temperature was slightly lower. The relative humidity was set between 20% and 35%. The environ- ment (temperature, relative humidity) of the incubator room was controlled. The room was ventilated, expelling air directly to the outside rather than re-circulating the same air. Fumi- gation was also undergone with eggs inside the incubator. The conjoined twins spontaneously died 24 h after the hatching; they were frozen and sent to the Unit of Veterinary Pathology of the University of Messina for gross examination. A radiographic examination was also carried out to analyse the skeletal malformations. Results The twins had two nearly opposite fused bodies, with one abdomen, two pairs of upper and lower limbs and one head that was completely turned at an angle of 90° on the vertebral Ó 2007 The Authors. Journal compilation Ó 2007 Blackwell Verlag www.blackwell-synergy.com Anat. Histol. Embryol. 36, 263–265 (2007) doi: 10.1111/j.1439-0264.2006.00748.x ISSN 0340–2096