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It's Foaling Time!

October 2018 by Dr Craig Simon
Craig has worked both in Australia and the United Kingdom since graduating from the University of Qld in 2000. He currently works in the busy ambulatory equine practice in South East Queensland, All Horses Veterinary Services. He has gained his Membership in the Australian and New Zealand College of Veterinary Scientists in the chapters of ‘Equine Surgery’ and ‘Equine Dentistry’.

So, it is now time for your mare to foal! All the sleepless nights have come to this. Hopefully you get to witness the event. But, what should you expect? What is normal? What is not normal? Should you seek further assistance by an experienced person or your local veterinarian?

The aim of this article is to give a brief, decisive overview of how a mare should foal under normal circumstances. Along with this will be a guide to some normal variations and examples of instances where further assistance is required.

Parturition in the mare, or the process of foaling, is unique. The powerful contractions enable this to be a relatively quick process. But, because of this, the foal and mare can get into trouble quickly if things aren’t going well.

So, become familiar with what to expect, make a judgment on whether the delivery is normal or not, get help if you need it and don’t panic!

Download this article to see a perfect foaling sequence in action! Click on the article image on the top right.

Is she ready to go?

The average gestation for a mare ranges from 340 to 342 days, however it is not unusual for her to foal a couple of weeks either side of this (320-362 days). So, there is a long period of time when a mare may foal and still be considered a normal gestation.

There is a complex balance of hormones which stimulate maturation of the foal and allow the mare to prepare for the birth. There will normally be udder development 2-6 weeks prior to foaling and they will often develop waxing on the tips of the teats 48-72 hours prior to parturition. It is worthwhile noting these signs as premature development of the udder or running milk may indicate a problem. Look out for relaxation and softening of the structures around the mare’s pelvis and perineum during the last week of pregnancy, as the ligaments and muscles soften in preparation for giving birth.

There can be great variation in the timing between these ‘signs’ mentioned above. More accurate methods have been researched over years in order to gain more insight into when a mare may foal.

Such predictive methods have been focused on changes in the mare’s milk in the days leading up to foaling. It has been shown that levels of calcium, potassium, protein and lactose increase, and the values of sodium and chloride decrease.

In particular, measurements of calcium carbonate in a sample of the mare’s milk can be used as an indicator of when a mare is getting close to foaling, as the levels increase rapidly within 72 hrs of the mare given birth.
An alternative indicator, measuring pH level in mare’s milk, has also been shown to be a useful method for assessing impending parturition.

pH levels drop dramatically also over the 72 hr period leading up to birth. So, monitoring the levels in the lead up period is important to notice this change.  Levels of pH - 6.5 or lower have been documented as the mare gets very close in the last 24 hrs.

Has she started foaling?

The foaling process is continual but has been described in three stages.

Stage One lasts for about an hour, but can range from 10 minutes to 5 hours. It is normal during this time for the mare to appear anxious, show signs of restlessness, walking, some sweating, or she may get up and down now and then. Getting up and down frequently, however, may signal a problem.

Stage One ends with the water breaking. At this time, the chorioallantois (foetal membrane) ruptures, allowing the passage of allantoic fluid, which has a brownish yellow appearance.

Is the foal coming?

Hopefully so! Stage Two is here. The mare has very forceful contractions at this point and the foal is normally delivered in 15-30 minutes. You should see a whitish membrane at the vulva - this is the intact amnion, inside which is the foal. This can be seen normally within 10 minutes of the water breaking.

Normal presentation of the foal at this point is important as it allows easy passage of the foal through the pelvic canal. Problems generally arise because the foal is not positioned correctly because of their long legs and neck or may have contracted tendons. Rarely are they oversized, however, Shetlands tend to have big skulls, which can get them into trouble. Young mares having their first foal also tend to be at more risk of developing problems when compared to the older, multiparous mare.

The first thing to appear should be one of the front feet, this is closely followed by the other foot and then the muzzle. The foal then generally passes fairly rapidly past this point. The foal on the ground will have the umbilical cord intact, which breaks when the mare stands. When it does break, the navel can be disinfected with a solution, such as 0.5% chlorhexidine.

If the so called ‘red bag’ appears, the foal can quickly become short of oxygen and become compromised or die. Here, the chorioallantois becomes separated before it should and a red velvety membrane appears at the vulva. The bag should be ruptured immediately.

I don’t think it is progressing normally!

A few points to note that may give indication of a problem:

  • The amnion should protrude within five minutes after the water breaking,
  • A red bag appears,
  • The mare has been pushing for 10 minutes and there is no sign of a foal.

When should the membranes (placenta) come out?

Finally, Stage Three of parturition is the passing of the foetal membranes or placenta. This usually occurs at about four hours after foaling. It is worthwhile keeping the membranes in a bag or wheelbarrow until your vet can check to confirm they have past in full.

The mare should be assessed by your veterinarian if this has not occurred because, as discussed below, retained membranes can cause serious illness, including septicaemia and laminitis. 

Retained placenta

Retained foetal membranes, known also as retained placenta is a very common post partum problem in the mare. The condition describes a failure of passage of all or part of the placenta after foaling. When managed correctly it is unlikely to have any serious consequences, however there are recognised complications that could affect future breeding or result in a debilitating lameness or even death.

The placenta is composed of the foetal membranes namely the amnion and allantochorion. After the foal has been delivered the mare should pass the placenta during the so-called third stage of labour.

The process is facilitated by uterine contractions, in which oxytocin plays a role, along with the weight of the freed placenta. It is usually uneventful; however, some mares can appear colicky due to the powerful uterine contractions. It is important to differentiate this from ‘real colic’, as mares that have just foaled are susceptible to intestinal displacements that may require surgical treatment. Any colic signs that are apparent after an hour post foaling need urgent veterinary attention.

Passing of the membranes usually takes about 15 minutes to 1 hour. If it is longer than 4-6 hours then the mare should be treated as an emergency.

Causes and risk factors for retained placenta

The portion of placenta that is typically still attached is in the non-gravid horn, which is the part of the horn not containing the pregnancy. It is here where the placenta is thicker and has deeper attachments.
Mares that are at risk of retaining the membranes include: sick mares, mares in poor condition, mares in which labour was induced, caesareans, prolonged gestations and older mares.

Retained placentas can occur in any breed or circumstance however the chances of serious complications developing increase in draft breeds and in mares that have had dystocia (or difficult births).

The dangers of retained placenta

Problems that can develop from a retained placenta include: metritis, septicaemia, laminitis, breeding problems or even death.

Left untreated the uterus can accumulate a soup of bacteria and toxins. Not only does the retained placenta allow a pathway for bacteria to enter, but the tissue breakdown (or autolysis) provides a great medium for bacterial growth.

The resulting inflammation within the uterus, leads to an increase in blood flow which allows toxins to be easily absorbed, potentially leading to septicaemia. In particular the endotoxins contained in the cell wall of gram-negative bacteria can cause severe illness or laminitis.

Signs that laminitis may be developing include a pottery gait, reluctance to walk, increases in the digital pulses or heat in the foot and shifting of weight. This condition can be debilitating to the horse.
Retained membranes have the potential to reduce pregnancy rates or delay return to service if infection is present. Any infection present needs to be resolved prior to breeding and scar tissue that can form may interfere with pregnancy.

Treatment

The aim of treating mares with retained placentas is to facilitate the removal of the membranes, without force, and to prevent further complications as described above.

In uncomplicated cases the treatment that is needed is minimal. These are cases in which the foetal membranes pass in a timely manner or with minimal effort.

Early oxytocin therapy may be helpful in older mares or mares that have previously had retained membranes. Oxytocin causes uterine contractions and can help push out the tissue. Although uterine contractions can be painful in some mares, oxytocin given at recommended  doses doesn’t usually have many side effects.

Do not cut the placenta as the weight will give gentle traction, which aids in removal. It is important to take care if assessing the ‘back end’ of the mare, as anxious, ‘foal proud’ mares may unexpectedly turn sharply or kick, causing harm to people or the foal.

In cases in which the membranes are retained for prolonged periods or in high-risk cases such as draft horses, more intensive therapy is required.

The treatment can be divided into two groups – local treatment of the uterus and placenta, and systemic therapy.

Localised treatment consists of removal of the placenta and removal of bacteria and toxins from the uterus. Removal of the membranes should not be forced. If they are not removed relatively easily it is better to wait and give appropriate medication.

Excessive traction can tear the placenta, cause severe haemorrhage or more inflammation that can be more problematic than the initial problem.

There are various techniques available for removal and the approach used will vary depending on the personal preference of the veterinarian. The uterus may also be flushed to help reduce the bacterial load. This can be augmented with intra-uterine antibiotics.

Systemic treatment describes the use of various drugs such as non-steroidal anti-inflammatories (eg. ‘bute’ or finadyne), antibiotics, oxytocin and fluid therapy in severe cases. Tetanus prophylaxis should be ensured.

Retained Placenta... What to do

  • Call the vet if the membranes have been retained for longer than 3 hours
  • Don’t pull on the placenta. This may cause the placenta to tear or cause haemorrhage
  • Don’t cut the placenta - its weight helps removal
  • When the placenta is passed keep it in a bucket away from wildlife and dogs and for assessment
  • Watch for signs of laminitis
  • Wait for the infection to be resolved before attempting breeding

Wrapping up

There are many potential problems that can develop during the foaling process that are beyond the scope of this article. Nevertheless, rather than getting caught up with all the potential problems and how to fix them, focus on becoming familiar with what is normal. Then, when things aren’t going well, you can be prepared to contact people that can help you - usually your vet.