Radiographic Mensuration of Caudal Vena Cava, Aorta, Vertebral Length and Fourth Rib Width and Ascertaining their Ratios in Healthy Dogs

Background: Caudal vena cava generally travels from the abdominal cavity to the right atrium and visible on lateral thoracic radiograph. Dilation of Caudal vena cava is generally considered as an abnormality for diagnosis of right-side heart failure. Normal range of ratio of caudal vena cava to associated structures can help in differentiating normal dogs from abnormal dogs. The present study was aimed to find such ratio in normal dogs and their clinical relevance. Methods: The present study was conducted on 19 healthy dogs of either sex belonging to different age-groups presented to the Department. They were anaesthetized and subjected to thoracic radiography in standard positions. The width of caudal vena cava (CVC), the descending aorta (AO), right fourth thoracic rib (R4) and the length of thoracic vertebrae (VL) were measured in left lateral (LeL) radiographic views to calculate ratios like CVC/AO, CVC/VL, CVC/R4, AO/VL, AO/R4. Result: The results revealed a wider range of some of such ratios than those reported so far by other workers for healthy dogs. Moreover, a wide variation in shape of CVC and size of R4 was noticed in individuals. It is concluded that the existing range of such ratio needs to be modified for better clinical relevance and overall such ratios do not represent a sensitive diagnostic modality.