Thoracic and Abdominal Radiologic Anatomy of the Greater Cane Rat (Thryonomys swinderianus).

Abstract

The greater cane rat (Thryonomys swinderianus) is widely distributed in sub-Saharan Africa, including western, central, eastern and southern Africa. It is the African's second-largest rodent. This study was done to describe and establish the normal reference values for radiographic anatomy of the thorax and abdomen in greater cane rats for biomedical and related research, teaching comparative veterinary anatomy and clinical uses. Radiography of the thorax and abdomen was performed under general anaesthesia in ten (10) wild adult greater cane rats. Right lateral (RL), left lateral (LL), dorsoventral (DV) and ventrodorsal (VD) radiographic projections of the thorax were taken. For the abdomen, RL and VD projections were obtained. All greater cane rats had 13 thoracic vertebrae with corresponding pairs of ribs. The number of lumbar vertebrae was mainly six. The sternum consisted of manubrium sterni, xiphoid process and four sternebrae. The anticlinal vertebra was mainly the 11th thoracic vertebra, and the sacrum consisted of four fused sacral vertebrae. Reference ranges for thoracic and abdominal organs/structures were established, such as the tracheal diameter (6.8 mm), angle between the mainstem bronchi (DV: 47.8°; VD: 46.4°), and gastric axis angle (77.6°). Further, ratios like the vertebral heart size (VHS) (RL: 9.70, LL: 9.83, DV: 10.46 and VD: 10.45), caudal vena cava diameter to length of thoracic vertebra above the carina (0.86), tracheal diameter to thoracic inlet diameter (0.32), and cardiothoracic (DV: 0.63, VD: 0.64) were calculated. Measurements of sternebrae, thoracic and lumbar vertebrae are provided. Differences and similarities with other rodents have been highlighted. Information from this research will serve as a reference for routine veterinary clinical procedures and biomedical studies and for teaching veterinary comparative anatomy and diagnostic imaging. Additionally, the use of ratios of absolute measurements of thoracic and abdominal organs/structures to relevant skeletal structures is recommended to overcome intraspecies variability in body size.