Rump Fat Measurement in Horses

Ultrasound may be used to measure subcutaneous fat thickness, also called rump fat thickness, in horses and help researchers ascertain body condition. A fixed anatomical point is typically used for this measurement: about 2 in (5 cm) lateral from the midline at the midpoint of the pelvic bone.

Researchers developed an equation using the ultrasound measurement to determine percentage of body fat:

% body fat = 2.47 + {5.47 (rump fat in centimeters)}

If, for example, the ultrasound reveals a rump fat measurement of 3.5 cm, the total percentage of body fat is 21.62% (5.47 x 3.5 cm = 19.15 + 2.47 = 21.62%).

Thin to moderate horses generally have body fat percentages in the range of 8-14, and overweight horses would typically have percentages in the 16-30 range.

Though this measurement is not designed for at-home use, it is valuable in experimental settings, especially during feeding trials in horses. The aforementioned equation was developed using horses from just a couple of breeds, so it may not be suitable for all applications, such as measuring especially small or large horses. Despite this, tracking the same horses over time and recording differences is one way for researchers to monitor body condition.

Download a body condition score chart.