The objective of this study was to non-invasively document the changes in
echocardiographic variables of left ventricular size and function during acute
normovolaemic anaemia. This model was developed as a pilot study with the purpose
of providing baseline information to investigate the pathophysiology, and more
specifically the effect on the heart, of canine babesiosis-induced anaemia. The study
group comprised of 11 mature healthy Beagle dogs that weighed between 9 and 15
kg. Severe normovolaemic anaemia was induced over a 3-4 day period by serial
bleeding while maintaining normovolaemia by autotransfusing plasma and infusing
crystalloids. The dogs were then allowed to recover. Pre-anaemic [mean haematocrit
(Hct) 46.7%, standard deviation (SD) 2.4%)] echocardiographic variables of left
ventricular size and performance were statistically compared to those in the severely
[mean Hct 15.3 %, SD 1.1%], moderately [mean Hct 24.7%, SD 1.5%] and mildly
[mean Hct 33.5%, SD 2.5%] anaemic states, and between the anaemic states. The
following variables were measured: left atrial size; left ventricular fractional
shortening, ejection fraction, end-systolic and end-diastolic ventricular volumes and
their derivatives [stroke volume, stroke index, cardiac output, cardiac index]; systolic
time intervals [left ventricular ejection time (LVET), pre-ejection period (PEP),
velocity of circumferential shortening, LVET/PEP and LVET index (LVETI)]; and
heart rate. With the exception of end diastolic volume, left atrial size, LVET/PEP and
LVETI, there was a statistically significant (p < 0.05) change in all variables in the
severely anaemic state versus the pre-anaemic and the mild and moderate anaemic
states. In accordance with previous invasive models, this study demonstrates the
hyperdynamic state of the left ventricle that develops in response to experimentally
induced acute canine normovolaemic anaemia in the conscious dog, and shows
promise as a non-invasive technique of evaluating the cardiac changes in dogs
suffering from canine babesiosis.
