Radiographic anatomy of the thorax in pet rabbits (Oryctolagus cuniculus)

This study aimed to describe the normal radiographic anatomy of relevant thoracic structures in clinically healthy pet rabbits and provide morphometric data for some of these structures in lateral and ventrodorsal radiographs.

Radiographs of 100 pet rabbits without clinical or radiographic signs of respiratory, cardiovascular, or mediastinal diseases were included in the study. The radiographic appearance of the aorta, the caudal vena cava, pulmonary vessels, the trachea, the delineation (visibility) of the cranial heart contour, and the extension of the diaphragm were evaluated using lateral radiographs. Additionally, the height of the trachea at 2 locations and the angle between the trachea and the thoracic spine were measured. On radiographs in ventrodorsal projection, the visibility of the cranial cardiac contour, the shape of the thorax, and the extension of the diaphragm were evaluated.

Thoracic radiographs of 100 pet rabbits, including 54 males (14 intact and 40 neutered) and 46 females (29 intact and 17 neutered) were included. The animals were aged between 6 months and 11 years (median 4.75 years) and had a median body weight of 1.8 kg (range: 0.8-2.7 kg). On the lateral projection, the aorta and vena cava were visible on all radiographs, whereas small pulmonary vessels were recognizable in only 61 animals. The cranial contour of the heart was well defined in 45 rabbits and moderately defined in 55 rabbits. The trachea was exclusively ventrally mineralized in all rabbits. Median tracheal height was 3.2 mm at the level of the first thoracic vertebra and 3.2 mm at the level of the fourth thoracic vertebra. The median angle between the trachea and thoracic spine was 11.6°. On the ventrodorsal projection, the cranial contour of the heart was well defined in 74 rabbits and moderately in 26 rabbits. The median diaphragmatic extension was at the level of the 7th thoracic vertebra.

Our study provides an overview of the thoracic structures visible on radiographs in pet rabbits weighing up to 3 kg. The results of our study contribute to the detection of pathological changes in the thorax.