Overview of Swine Congenital Malformations Associated with Abnormal Twinning

Abstract

A review of congenital malformations in swine relating to abnormal twinning was carried out. The aim was to describe and estimate these defects. Among the recorded twins, the most common defect was the syncephalus thoracopagus or cephalothoracopagus. A couple of dicephali and diprosopus congenital anomalies were also registered. At last, some cases of thoraco-omphalopagus piglets were surveyed. There was also a report of an acardiac twin (hemiacardius acephalus) and a case of a conjoined parasitic twin. The pathogenetic mechanisms of this condition, frequently reported in veterinary practice, are discussed. The importance of embryonic imperfect twinning is commonly associated with dystocia.

Keywords: congenital malformations; conjoined twins; pig; teratology.

Figure 1

(a) Two-headed piglet [9], (b) Dipygus pig [10], (c) Prosopothoracopagus disymmetros [11], (d) Diprosopus dipygus [8], (e) Epigastricus parasite [10], (f) Thoracopagus diplopagus [12].

Figure 2

(aI,aII) Cephalothoracopagus monosymmetros tetrophthalmus synotos tetrabrachius [11], (bI,bII) Dicephalus parapagus [13], (cI,cII) Cephalothoracopagus monosymmetros synotos tetrabrachius craniis a latere coalitis [11], (d) Cephalothoracopagus monosymmetros biauritus tetrabrachius [11], (e) Syncephalus pig [10].

Figure 3

Studied case of the two conjoined piglets: the external gross view in a lateral (a) and in a supine position (b) before necropsy; a panoramic X-ray image in a supine position (c); and a panoramic gross view of the opened body cavities, showing the single enlarged heart and the other internal organs (d). The notable findings in each image are described in detail in the above text (Section 2.3.). Personal archive of Assistant Prof. Dimitrios Doukas.