Histomorphometry of the placental vasculature and microcotyledons in Thoroughbred mares with chronic laminitis.

The given research article discusses a study where the placental vasculature and microcotyledons in pregnant mares with chronic laminitis were examined. Results showed that these mares exhibited signs of high blood pressure, abnormalities in placental vessels, and gave birth to foals with lower birth weight and shorter gestation lengths.

Objective of the study

• This research aimed to evaluate the structure and condition of the placental vasculature and microcotyledons in pregnant equine mares suffering from chronic laminitis.

Methodology

• A total of 26 pregnant mares were included in the study. These were divided into two groups: the Laminitis Group, consisting of 13 mares with chronic laminitis and the Healthy Group, made up of 13 healthy mares.
• Different metrics like arterial systolic pressure and heart rate were measured during the last 30 days of gestation.
• Post-foaling, the fetal membranes were evaluated visually, and some samples were harvested for histopathologic examination.
• Digital images from the chorioallantois of each mare were taken and analysed with NIH ImageJ software for various parameters including: arterioles from the allantoic region’s total lumen and vascular wall, microcotyledonary and capillary area per field.

Findings

• The Laminitis Group showed indications of hypertension, reduced gestational length, decreased placental weight, and lower birthweight compared with the Healthy Group.
• Mares with laminitis showed reduced vascular lumen diameters in the uterine body and pregnant horn, along with wall thickening in the pregnant horn.
• They also displayed smaller capillary areas per field in the microcotyledons of uterine body and pregnant horn.

Conclusion

• The study concluded that chronic laminitis in pregnant mares leads to signs of hypertension syndrome and vascular abnormalities in placental vessels. These abnormalities include reduction in the vascular lumen and capillary area of the microcotyledones, coupled with thickening of the vascular wall.
• This condition also affects the offspring, as the foals born from mares with chronic laminitis showed lower birth weight and shorter gestation lengths.