Morphology of a two‐headed piglet

Abstract

A live-born, one-day-old diprosopic piglet was presented to the Ontario Veterinary College. The piglet had a normal body with two heads, joined in the occipital region. There were two complete snouts, four eyes and three ears. The lower jaws were immobile because of overlapping mandibular rami. Although there was only one vertebral column, the bodies of the vertebrae, but not the neural arches, were doubled from the axis to T8. There was one thyroid gland and one larynx and hyoid apparatus. The two tongues were joined at their base just rostral to the single epiglottis. The palate was completely split in the right head but only partially split in the left. the cranial nerves were normal and doubled except for IX, X and XI. The brains were fused at the pon-medulla junction. An anomalous midline tag of neural tissue resembling remnants of the medical halves of two nervous systems extended form this point to the level of T8. Possible developmental mechanisms and rates of incidence are discussed.

Conjoined twin piglets with duplicated cranial and caudal axes

“…This case differs from the three previous anatomical descriptions of porcine diprosopic animals (Bishop, 1908(Bishop, , 1921(Bishop, , 1923Thuringer, 1919;Partlow et al, 1981). Bishop (1908Bishop ( , 1921Bishop ( , 1923 described in detail only the nervous system, heart, and anterior arteries of a 22 mm pig embryo.…”

“…It had two normal eyes laterally, with two fused eyeballs medially, similar to the embryo described by Bishop (1921Bishop ( ,1923). Thuringer's twins had two normal ears (laterally) in addition to ear rudiments medially, similar to the twins of Partlow et al (1981). Also, the morphology of the pharyngeal area was more similar to the present case, as the twins exhibited two tongues fused at their base, plus the appearance of a rudimentary tongue attached to the roof of the pharynx.…”

“…As the internal details were derived from serial sections, comparisons are difficult. The piglet described by Partlow et al (1981) was more extensively doubled in the facial region than the present case, having four eyes and three ears. A single, normally oriented epiglottis and esophagus were described.…”

“…There. are only three other detailed anatomical descriptions of diprosopic pigs in the literature (Bishop, 1908(Bishop, , 1921(Bishop, , 1923Thuringer, 1919;Partlow et al, 1981). This is the first anatomical analysis of a diprosopic, dipygic pig.…”

Cephalothoracopagus (monocephalic dithoracic) conjoined twins in a pig (Sus scrofa f. domestica): a case report

“…Various types of conjoined twins in the pig were reported by Partlow et al (1981), McManus et al (1994) and Mostafa et al (2005). However, cephalopagus in this species was not thoroughly investigated and described.…”