A morphometric study of foetal and newborn cardiac growth in the horse.

The research article details a study on the growth of the heart in horse fetuses and newborn foals, highlighting the changes in size, dimensions, thickness, and associated vessels during the late stages of pregnancy and days following birth.

Objective and Methodology

• The study aimed to examine and quantify the rate of growth and changes in the heart structure of equine fetuses and newborn foals.
• 81 equine fetuses, aged between 190 to 330 days, and 26 newborn foals were chosen as the subjects of the study.
• Data gathered included the mean weight, external dimensions, ventricular wall thickness, and circumference of the atrio-ventricular orifice. Information concerning the main vessels associated with the heart was also recorded.

Findings: Foetal Heart Growth

• It was discovered that all cardiac measurements of the fetuses increased linearly throughout the latter half of pregnancy and showed a strong correlation with fetal age.
• The same linear pattern of growth was also noted in the parameters of the associated arterial trunks.
• From Day 190 to term, the ratio of the right ventricular weight to the total ventricular weight in the equine fetuses saw a gradual increase from 0.27 to 0.34.

Findings: Newborn Foal Heart Growth

• In contrast, in newborn foals, the ratio of the right ventricular weight to the total ventricular weight began to decrease soon after birth, declining from 0.32 at birth to 0.28 by day 11.

Morphological Observations

• Regarding the thickness of different parts of the heart, the interventricular septum was found to be the thickest, followed by the right ventricular wall. The left ventricular wall was found to be the thinnest during the gestation period under study.
• Interestingly, the right ventricle was found to be 3.2 per cent to 31.5 per cent thicker than the left ventricle throughout fetal and early neonatal life.