Heart Size Measurement in the New Zealand White Rabbit by Cardiothoracic Ratio

Aim: Assessing the heart and other thoracic structures radiographically is very important, in small animal practice, when decisions must be made regarding staging a patient with the suspected cardiac anomaly, deciding about therapy protocols, and monitoring disease progression or response to treatment. The present work was carried out to generate a value for radiographic measurement of heart size in the New Zealand White (NZW) rabbit by the cardiothoracic ratio (CTR).

Materials and Methods: Ten healthy NZW rabbits were used for the study. A dorsoventral (DV) thoracic radiograph was obtained in each of the animals. Cardiac and thoracic diameters of the ten rabbits were evaluated to determine a reference value of CTR in normal NZW rabbits.

Results: Mean plus or minus standard error of mean (M±SEM) CTR were 0.54 ± 0.01. There was not a significant difference between male (0.54 ± 0.01) and female (0.54 ± 0.01) CTR values. There was no correlation between sex and CTR.

Conclusion: In clinical practice, the application of CTR in radiographic assessment of the heart is objective and very easy.