Normal edema at term and ventral rupture

Keywords: ventral, edema, rupture, equine, mare, foaling, pain

The plaque of ventral edema shown below (arrows) is typical of late gestation in mares.

Image size: 1200 x 890 px

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.

Image size: 1500 x 2102 px

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

Musculoskeletal pain and ex-copula ejaculation

Key words: stallion, equine, pain, ejaculate, ex-copula

Stallions may fail to mount and ejaculate because of severe musculoskeletal pain.  In this case, a 3-year old Standardbred stallion was unable to copulate because of severe degenerative joint disease in both stifle joints:

Image size: 764 x 804px

The owner was advised against breeding because of potential heritability of conformational defects. Nevertheless, the option to attempt to collect semen from the stallion was adopted.
Several fruitless attempts were made to collect semen by standing collection (non-mounted collection) using a tease mare and an artificial vagina. Therefore a system was prepared for ex-copula semen collection. This consisted of a ring of polyethylene tubing (joined with a plastic tubing connector) attached to a plastic sleeve with cable ties. The hand of the sleeve was removed and the sleeve was shortened. A conventional filter and "Whirl-pak" was attached to collect the semen. The apparatus was suspended beneath the preputial opening using tail bandages as shown here:

Image size: 969 x 642px

A tricyclic antidepressant imipramine (total dose 1,5 g per os) was used to obtain ejaculation, followed 2.5 hours later with 350 mg of xylazine.  These are both tricyclic compounds, known for their ability to produce erections and in combination, ejaculation, more reliably than when used alone.

As shown here, related tricyclics are also known to produces partial erection and in some cases, even priapism (pathologically prolonged erection).

Image size: 1272 x 1073px

The stallion attained partial erection and a small ejaculate was produced:

Image size: 1071 x 822px

This ejaculate contained 1.1 billion spermatozoa (most normal ejaculates contain between 3.5 to 12 billion in our experience) and almost all of the sperm had loose-heads. The motility of the sample was zero.

On the afternoon of that same day, the stallion was given 500 mg of flunixin meglumine intravenously. After a one hour, and in the presence of a mare in estrus, the stallion mounted a phantom after several attempts and ejaculated a substantial, normal ejaculate with excellent motility. 

This case demonstrated that a single ex-copula ejaculate may not be an accurate reflection of semen quality. Also, appropriate analgesia may be helpful in these cases.