Polymelia, vent duplex, cloacal bursa duplex and triple caeca in a broiler chick

Abstract

Congenital abnormalities are common among avian and mammalian species. They could be partial or total drift from the normal structural organization of the organ-systems. This article is aimed at reporting the occurrence of multiple abnormalities in a 3-week-old broiler chick. Ante mortem, post-mortem, radiological and osteological investigations were carried out, to ascertain the number and form of abnormalities present in the chick. A total of four different congenital abnormalities were discovered in this chick. These include: polymelia (presence of supernumerary or accessory limb which is usually malformed); double vents (vent duplex); double cloacal bursae (bursa duplex) and triple caeca. Radiological and postmortem examinations revealed the attachment of the accessory limb to the caudal depressor muscle as a form of synsarcosis, via a tendon that originated from the deep fossa of the modified femoral head of the accessory limb. The right vent was patent whereas the left was not. The two cloacal bursae were almost the same size, while the three caeca showed slight variation in length but typical features of the avian caecum (base, middle (body) and apex) were clearly visible. However, most cases of congenital anomalies in the avian species occur as multiple defects, with the most common being polymelia. The latest finding in this report is the discovery of double cloacal bursae (bursae of Fabricius), which has not been reported in the avian species.

First Report of Polymelia in a Passerine Bird, the Pied Flycatcher

“…Malformations in birds have been described mainly by Pourlis (2011) summarizing anatomical characteristics, signs, symptoms and habitat. So far, polymelia has been reported mainly among poultry (Abu-Seida 2014, Hassanzadeh & Rahemi 2017, Plang et al 2021). Our finding is highly relevant to science given the difficulty of finding this type of malformation in wild passerine birds due to their expected low viability in nature.…”

“…Unlike in other animals, polymelia has not been commonly observed in birds. So far, it has been reported among broiler chickens and other farming fowls (Abu-Seida 2014, Hassanzadeh & Rahemi 2017, Plang et al 2021, Snyman et al 2022. The only cases reported in wild birds are the Swainson's Hawk Buteo swainsoni (Rogers et al 2016) and the White Stork Ciconia ciconia (Onmuş 2017).…”