Amniotic Plaques, Hippomanes and Cervical Star

Amniotic plaques, hippomanes, and the cervical star are all normal, incidental findings that can be observed during the pregnancy of a mare.

These structures are typically seen during veterinary examinations or ultrasound imaging and are important markers in monitoring the health of the mare and her fetus.

Amniotic Plaques

Amniotic plaques are small, white or translucent areas found on the inner surface of the mare’s amniotic sac during pregnancy.

Most noticeable during 3-7 month of gestation. Number varies widely and consists of edematous epithelial cells that are sometimes keratinized.

Amniotic proliferations are found to a lesser degree in horses, sheep and goats but not in swine and carnivores. Etiology and significance is not known and they are apparently not due to infectious agents either bacterial or viral and there are no inflammatory lesions associated with these plaques. These plaques are localized squamous proliferations called verrucae.

Hippomanes

Hippomanes are soft, irregularly shaped, and gelatinous masses that can be found in the amniotic fluid of pregnant mares.

The cow, horse, sheep, goat and pig allantoic fluid contains amorphous, semisolid, amber coloured, soft, pliable, rubber like, irregular shaped masses or bodies, thinner at the edges and thicker in the center 2.5-15.0 cm in diameter and from 0.3-3.8 cm in thickness floating in the fluid. These bodies are called as Hippomanes.

Cervical Star

The cervical star is a distinct, star-shaped area on the inner surface of the mare’s cervix that is visible during pregnancy.

Cervical star reflects the contact area between the cervical folds and the chorion. The epithelium of the cervix lacks the crypts to connect with the villi of the chorion. Its an irregular bare spot in the diffuse placenta of the chorion is found over the internal os of the cervix.