Hemodynamic monitoring is a crucial component of intensive care medicine, as it allows early identification and treatment of hypovolemia. The ultrasonographic assessment of the caudal vena cava-to-aorta ratio (CVC:Ao), as already reported and routinely employed in clinical practice for dogs, has proved to be a valuable and noninvasive method for early recognition of the intravascular volume status of the patient. Reference intervals for CVC:Ao in pet rabbits have not been previously described in the literature. The primary objectives of the present report were to describe feasibility, ultrasonographic technique, and reference intervals for the CVC:Ao ratio using ultrasound in a population of healthy pet rabbits of various age, breeds, and of both sexes, presented for elective ovariohysterectomy and orchiectomy. Secondary objectives include variations of CVC:Ao ratio depending on signalment (age, weight, sex), physical exam findings, and hematological parameters (blood gases, packed cell volume, total solids). The present study provides a description of a simple ultrasonographic method and reference parameters for use in a clinical setting to assess and monitor intravascular volume status in rabbit patients.