Echocardiographic Changes in Heart Size in Hypohydrated Horses

Abstract

Background: Hypohydration causes transient echocardiographic changes in pigs, dogs, humans, and cats. These changes mask the diagnosis of some cardiac diseases (valvular regurgitation, dilated cardiomyopathy) and promote the diagnosis of others (hypertropic cardiomyopathy and infiltrative disease), thus inhibiting accurate echocardiographic evaluation.Objectives: To describe the echocardiographic changes associated with hypohydration in normal horses. Animals: Ten adult horses without detectable cardiac disease. Methods: Experimental study. Echocardiographic examinations were performed on horses in the euhydrated and hypohydrated states. Horses were hypohydrated by combined water deprivation and furosemide administration until a 4-7% reduction in bodyweight was achieved. Statistical analyses were performed by paired t-tests.Results: Hypohydration decreased left ventricular internal diameter in systole (0.8 AE 0.6 cm) and diastole (1.7 AE 0.9 cm), left atrial diameter (1.5 AE 0.4 cm) and left ventricular volume (490 AE 251 mL) (P-values o .01), and increased septal wall thickness in diastole (0.6 AE 0.3 cm), free wall thickness in diastole (0.5 AE 0.3 cm), mean wall thickness (0.5 AE 0.2 cm) and relative wall thickness (0.2 AE 0.1 cm) (P-values o .01).Conclusions and Clinical Importance: Hypohydration produces changes in left ventricular and atrial size that could mask or promote the severity of cardiac disease. The thickened, ''pseudohypertrophied'' appearance of the left ventricle in hypohydrated horses could affect interpretation of echocardiographic variables that are applied to the prediction of athletic performance. Echocardiography may prove a noninvasive method of monitoring volume status and response to fluid therapy in hypovolemic horses.

Left Ventricular Function After Prolonged Exercise in Equine Endurance Athletes

“…A clinical evaluation of the hydration status including skin tent duration was also performed; however, as such clinical variables have been shown to be poorly correlated with plasma osmolality it was chosen not to include them in the statistical analyses . Hypohydration has been shown to affect multiple echocardiographic variables pertaining to LV dimensions in horses hypohydrated to 4–7% of their bodyweight . The decreases in LA diameter, LV systolic and diastolic diameter and diastolic volume were generally comparable or somewhat bigger than those observed in this study.…”

Clostridial myonecrosis, haemolytic anaemia, hepatopathy, osteitis and transient hypertrophic cardiomyopathy after intramuscular injection in a Thoroughbred gelding

“…The pertinent echocardiographic changes in the present case include reversible concentric left ventricular hypertrophy with decreased size of the left ventricular cavity. It is recognised that hypohydrated horses can have changes in the size of both the left ventricle and atrium that may be interpreted as hypertrophy, termed ‘pseudohypertrophy’, as the cardiac abnormalities resolve with correction of dehydration . The first cardiac ultrasound examination of the present horse was performed on day 5 post‐admission when hydration status was considered normal as assessed by normal lactate and urine output.…”

Hypertrophic cardiomyopathy in a Clydesdale gelding

“…Reported findings in horses include thickening of the IVS and LVFW at end‐diastole and peak systole and a reduction in the LV internal diameter, also at end‐diastole and peak systole . In a report of five suspected cases of hypertensive cardiomyopathy, the RWT ranged between 0.57 and 1.26, compared with a normal value in non‐draught breeds of 0.47 . This coincided with mean non‐invasive blood pressure measurements that varied between 126 and 222 mmHg.…”