Equine hydrallantois is associated with impaired angiogenesis in the placenta.

INTRODUCTION: Hydrallantois is the excessive accumulation of fluid in the allantoic cavities during the last trimester of pregnancy, leading to abdominal wall hernias, cardiovascular shock, abortion, and dystocia. It has been postulated that hydrallantois is associated with structural and/or functional changes in the chorioallantoic membrane. In the present study, we hypothesized that angiogenesis is impaired in the hydrallantoic placenta. METHOD: Capillary density in the hydrallantoic placenta was evaluated in the chorioallantois via immunohistochemistry for Von Willebrand Factor. Moreover, the expression of angiogenic genes was compared between equine hydrallantois and age-matched, normal placentas. RESULTS: In the hydrallantoic samples, edema was the main pathological finding. The capillary density was significantly lower in the hydrallantoic samples than in normal placentas. The reduction in the number of vessels was associated with abnormal expression of a subset of angiogenic and hypoxia-associated genes including VEGF, VEGFR1, VEGFR2, ANGPT1, eNOS and HIF1A. We believe that the capillary density and the abnormal expression of angiogenic genes leads to tissue hypoxia (high expression of HIF1A) and edema. Finally, we identified a lower expression of genes associated with steroidogenic enzyme (CYP19A1) and estrogen receptor signaling (ESR2) in the hydrallantoic placenta. DISCUSSION: Based on the presented data, we believe that formation of edema is due to disrupted vascular development (low number of capillaries) and hypoxia in the hydrallantoic placenta. The edema leads to further hypoxia and consequently, causes an increase in vessel permeability which leads to a gradual increase in interstitial fluid accumulation, resulting in an insufficient transplacental exchange rate and accumulation of fluid in the allantoic cavity.

[Possibilities and limits for therapy of amniotic hydrops in cattle. A review]. / Möglichkeiten und Grenzen der Therapie der Eihautwassersucht beim Rind. Ubersichtsreferat.

The review describes the occurrence, causes and clinical signs of bovine placental hydrops. Furthermore prognosis, operative and hormonal treatment possibilities for interruption of pathological gestation as well as subsequent treatment are discussed.

Hydrops amnii in a mare.

A multiparous pregnant Welsh Pony mare was examined because of anorexia, dyspnea, and a large abdomen. Ultrasonography of the uterus revealed an excessive amount of amniotic fluid surrounding the fetus. Transabdominal ultrasonography permitted differentiation of hydrops amnii from hydrops allantois. The mare aborted a 7-month-old fetus with brachygnathia and a large, edematous umbilical cord. Hydrops amnii, an excessive accumulation of amniotic fluid in the amniotic cavity, is most commonly reported in cattle and sheep.

Hydrallantois in a ewe.

Hydrallantois was detected in a pregnant ewe by physical examination and ultrasonographic evaluation. Clinical signs of disease included acute progressive bilateral abdominal distention, anorexia, and recumbency. Right-flank celiotomy and cesarean section were used to alleviate the condition. Post-operatively, in addition to supportive treatment, oxytocin and fenprostalene (a long-acting prostaglandin) were administered to decrease the likelihood or severity of hydrallantoic sequelae.

Hydramnios causing uterine rupture in a mare.

An 18-year-old mare, 285 days pregnant, was evaluated for apparent abdominal pain of 8 hours' duration. A large volume of sanguinous fluid was obtained on abdominocentesis, and digital vaginal examination revealed a dilated cervix and blood in the uterus. Abdominal palpation per rectum revealed the uterus to be large and distended with fluid. Ultrasonography revealed a dead fetus on the floor of the cranial portion of the abdomen. The mare was euthanatized, and necropsy confirmed that the uterus had ruptured, and that the fetus, within its chorioallantois, was in the abdomen. The amniotic sac contained approximately 96 L of amniotic fluid. Torsion of the amniotic sac separated the fetus from the fluid-filled compartment. Hydramnios was diagnosed on the basis of the excessive amniotic fluid and was believed to be the cause of the uterine rupture.

Hydrops amnii in sheep associated with hydranencephaly and arthrogryposis with wesselsbron disease and rift valley fever viruses as aetiological agents.

During the 1974/75 lambing season numerous reports were received from various parts of the Republic of South Africa and South West Africa of severe abdominal distension in ewes after vaccination with the attenuated Rift Valley fever and/or attenuated Wesselsbron disease vaccine. The ewes were vaccinated at different stages of gestation in spite of recommendations to the contrary, the syndrome being especially obvious in ewes immunized with one or both of these vaccines during the first trimester of pregnancy. In some of the flocks hydrops amnii was recorded in as many as 15% of the ewes. Many of the ewes so affected showed a prolonged gestation of up to 6-7 months and, towards the end of gestation, were unable to rise or walk. They eventually died of ketosis, hypostatic pneumonia and complications due to dystocia. The foetuses examined were malformed and larger than normal with a mass of 3,6-6,7 kg. They usually showed arthrogryposis, brachygnathy inferior, hydranencephaly, hypoplasia or segmental aplasia of the spinal cord and neurogenic muscular atrophy. The amnion contained 8,0-18,0 1 of amniotic fluid, the endometrium was oedematous, and cystic tube-like dilatations, 1-10 mm in diameter, filled with a clear fluid, were scattered in the endometrium. No definite conclusions as to the aetiology of the syndrome could be drawn from serological tests performed on the ewes, lambs or foetuses. Preliminary experimental work confirmed previous observations that the attenuated Wesselsbron disease vaccine virus is responsible for this syndrome and that the wild-type virus is also implicated. In addition, the attenuated Rift Valley fever vaccine virus was found to the responsible for arthrogryposis and hydranencephaly without hydrops amnii and for micrencephaly and arthrogryposis associated with hydrops amnii in the ewe.