Normal edema at term and ventral rupture
Keywords: ventral, edema, rupture, equine, mare, foaling, painThe plaque of ventral edema shown below (arrows) is typical of late gestation in mares.
The affected area pits on pressure but the mare shows no discomfort at all. This makes this condition very different from impending rupture of the ventral abdominal structures. That condition is shown below.
Impending rupture of ventral abdominal structures during late gestation.
A massive ventral plaque of edema (more obvious than the usual ventral edema of late gestation) and the painful gait of the mare are indicators of this condition. As shown in inset A, ventral edema may be so severe that the architecture of the mammary gland is largely obscured. Severe edema is also illustrated at lower left where the margin between the plaque of edema and the ventral abdomen is indicated by red arrows.
Monitoring of milk electrolytes should be used to decide when to induce foaling. If the mare is off site, milk for electrolyte analysis can be collected by the owner. Assistance may be required during foaling. It has been suggested that minimal intervention is perhaps better that induction of foaling but that decision depends on prevailing conditions. In other words, if the mare is at a referral institution where 24 hour monitoring is possible, it may not be advisable to induce foaling. That is because induction of foaling is potentially hazardous, especially if it is done prematurely. In such cases, one would expect a higher incidence of failure of passive transfer and because the foal is not mature, a higher incidence of dystocia as well (movement into the correct position and posture is largely a function of fetal maturity).
After foaling, ventral edema usually subsides quickly enough to allow suckling (inset B). Otherwise, plasma transfusions may be given to prevent failure of passive transfer in the foal
If possible, the mare's abdomen should be supported until she can be induced to provide a viable foal. Supports can be made from wide elastic bandage i.e. Elastoplast TM, or a similar adhesive or partially adhesive bandage. Alternatively, a custom made support system can be used, such as that shown here.
Image size: 1200 x 1000px. Copyright Dr G. Colbern. gtcolbern@gmail.com
Although the condition is often referred to as "rupture of the prepubic tendon" antemortem examination using ultrasound and posrtmorten examination in euthanized mares has shown that rupture may involve the prepubic tendon, the rectus abdominus muscle, the transverse abdominal muscles or oblique abdominal muscles.
Surgical reconstruction of the abdomen has been described but the long term success of those cases as broodmares is not known. Soon after foaling, damage to abdominal is no longer visible so it may be tempting to re-breed these mares. This is not recommended because the condition is known to reoccur in subsequent pregnancies.
References:
Blanchard, T.L. et al. 1987. Hydroallantois in two mares. Equine Vet J. 222-225
Ross, J et al. 2008. Body wall tears during late pregnancy in mares: 13 cases (1995–2006) J Am Vet Med Assoc. 232:257–261
