You may print off our Caudal Vena Cava Maximum Height Measurement Chart first published in Vet Clinics of North America Small Animal Practice 2020– Click here for printable PDF.

The power of this approach is that we have provided absolute values over complicated exponential formulas.  We like too say “flat is flat.”  A “flat” caudal vena cava (CVC) is obvious and measurements of 3-5mm are within margins of error for most of us non-radiologists.  However, “FAT” is helpful as small dogs should be < 1.0cm, larger dogs > 9kg should be < 1.5cm (and now cats should be < 0.5cm with some more recent clinical research by Barron et al. J Vet Cardiol 2023.

However, the use of FAT CVC is more clinically useful.  Dogs < 9kg (<20lbs) should not have a maximum height of >1.0cm and dogs >9kg (>20lbs) should not have a maximum height of over 1.5cm as listed on our chart.  The eyeball characterization of FAT, flat or bounce, should always trump absolute height measurements.  Hepatic venous dissension, referred to as the “Tree Trunk Sign” is nearly 100% specific for increased right-sided filling pressures and right-CHF.  Gallbladder wall edema may also be caused by right-sided CHF – see IM Blog.

We measure using calipers as shown in the image using B-mode (M-mode not necessary and takes more time).  Always archive the image.

Please credit “Dr. Gregory Lisciandro, DVM, DABVP, DACVECC of FASTVet.com and Hill Country Veterinary Specialists, Spicewood, Texas” for the chart below if you use it in your presentations.  Send any comments to Dr. Greg Lisciandro at FASTSavesLives@gmail.com