Computed tomographic features of the normal spleen in rabbits (Oryctolagus cuniculus domesticus)

Computed tomography is commonly utilized for investigation of rabbits, and more recently, for evaluating abdominal pathology. The spleen, however, is an often-overlooked organ, with limited information published. The aims of this retrospective, observational, study were to document the visibility, size, and shape of the normal rabbit spleen and potential correlations with signalment. Institutional imaging archives were reviewed for diagnostic-image-quality abdominal CT studies of rabbits. In 115 cases, the inclusion criteria were met. Pre- and postcontrast CT studies were evaluated by two reviewers for visibility of the spleen. For precontrast CT images, the interrater agreement for identification of the spleen was fair. For postcontrast CT images, interrater agreement was moderate. There were significantly more spleens clearly identified on postcontrast studies compared with precontrast CT. Splenic location, volume, shape, X-ray attenuation, and length were measured, and the splenic-volume-to-body-weight ratio was calculated. The mean splenic volume was 1 mL (range 0.2-3.9 mL), mean length 40 mm (range 20-61 mm), mean attenuation (precontrast CT 80 HU and postcontrast CT 320 HU), and mean splenic volume/body weight ratio was 0.5 mL/kg (range 0.17-1.2 mL/kg). There was a significant relationship between splenic volume and body weight, which was weakly positively correlated. There was no correlation between splenic volume, age, and sex. The most commonly identified splenic shapes were "banana", "tongue", and "elephant trunk". The rabbit spleen can be identified on CT images, but more reliably on postcontrast CT images, which underlines the usefulness of contrast-enhanced CT in this species.