Ultrasonographic measurement of spleen volume in horses

Abstract

Ante-mortem measurement of spleen size may be valuable to understand and study hemodynamic changes during exercise and in clinical determination of splenomegaly. The hypotheses were that spleen volume can be calculated from transcutaneous ultrasonographic measurements in live standing horses; and that the spleen volume is proportional to blood volume, maximal under the influence of detomidine and minimal under the influence of epinephrine. Eight donated horses free of splenic disease were studied. Ultrasonographic spleen volume and Evans blue dye-dilution blood volume were measured before (baseline) and after intravenous administration of detomidine and epinephrine (separately). Spleen volume was calculated using a standard ellipsoid formula (VOLstandard) and with the formula modified for the unique shape of the equine spleen (VOLmodified). Horses were euthanised using pentobarbital sodium, spleens removed immediately and measurements repeated on the removed spleen. Descriptive statistics, correlation and regression analysis were performed. Mean VOLstandard was 31.4±9.8 litre at baseline, 34.0±10.5 litre after detomidine, and 5.4±3.1 litre after epinephrine. VOLmodified was 25.1±9.1 litre at baseline, 27.4±9.6 litre after detomidine, and 4.2±2.4 litre after epinephrine. Post-mortem spleen volume was 14.1±4.6 litre and was correlated with VOLstandard (r=0.86, P=0.006) and VOLmodified (r=0.87, P=0.004). Blood volume was correlated with VOLstandard (r=0.81, P=0.014) and VOLmodified (r=0.78, P=0.02). Packed cell volume after epinephrine was correlated with VOLstandard (r=0.95, P<0.001) and VOLmodified (r=0.96, P<0.001). When compared to baseline, spleen volume was smaller after epinephrine (P=0.009) but not larger after detomidine (P=0.12). Blood volume after epinephrine was larger than after detomidine (P=0.009). The study demonstrated that splenic size, under various pharmacological influences, can be calculated from ultrasonographic measurements in the live standing horse. Packed cell volume after epinephrine was the best indicator of spleen volume.

Effect of a long‐term high‐energy diet on cardiovascular parameters in Shetland pony mares

“…However, measurements were only performed once, and thus no definitive conclusions can be drawn. The PCV did not differ between HE and control mares, which is in agreement with the absence of a difference in splenic size, because a strong correlation between PCV and splenic volume has been described previously 26 …”

“…Splenic volume and PCV were measured at the end of study year 2014 (4 control mares [A‐D] and 7 HE mares [K‐Q]). Ultrasonographic splenic volumes were calculated using measurements obtained with a 3‐7 MHz large convex array transducer on an ultrasound machine as described previously 26 . Splenic volume was calculated using transabdominal and transthoracic measurements as described previously 26 .…”

“…Ultrasonographic splenic volumes were calculated using measurements obtained with a 3‐7 MHz large convex array transducer on an ultrasound machine as described previously 26 . Splenic volume was calculated using transabdominal and transthoracic measurements as described previously 26 . Ultrasonographic measurements of the spleen included: maximal length ( L ), width ( W ), and maximal thickness ( T max ) at the flank and at each intercostal space.…”

Cardiovascular findings in ponies with equine metabolic syndrome

“…21,51 No difference in ultrasonographic splenic volume was identified between groups in the present study, and this potential marker of sympathetic tone was not useful in the evaluation of the ANS in ponies with EMS. The tone of the splenic capsule has been proposed to reflect the tone of the capacitance vasculature, which makes splenic size an interesting noninvasive target for assessment of autonomic input.…”

Blood Transfusion in Equids—A Practical Approach and Review

“…Horses respond to increased oxygen demand by sympathetic vasomotor contraction of the spleen to mobilize sequestered erythrocytes into circulation, in response to both acute and chronic demand. In the most extreme circumstances, an adult horse can double their PCV with splenic contraction [ 5 , 6 , 7 ], and this must be taken into account when evaluating PCV, particularly in the face of acute blood volume changes.…”