Dr Vivienne Duggan of UCD’s veterinary college offers timely medical advice for all those expecting a foal this spring

The birth of a foal is like a carefully choreographed dance between the pregnant mare and her fetal foal. The mare nourishes the developing fetal foal, providing nutrients and oxygen. At full term the mature fetal foal takes over and drives the onset of the birth process through the release of hormones from its adrenal gland. Once born, the foal nurses, and this stimulates oxytoxin release from the mare’s pituitary gland. This helps the mare to expel the placenta and encourages the uterus to return to a normal size in preparation for the next pregnancy. If any one thing goes wrong everything gets out of step and this can affect the chances of the mare going back in foal in a timely manner.

There are a number of critical periods during which you can influence in a positive way, the chances of a mare going back in foal and not suffering long term complications that will affect her fertility and potentially her life. The key is to know what could go wrong and to recognise when something is wrong. Complications that may arise during the birth process, and subsequently, include trauma to the reproductive tract, either internally or externally, bleeding which may or may not be externally visible, failure to pass the placental membranes or cleanings, and infection in the uterus with the absorption of toxins into the blood resulting in laminitis.

Critical period 1: Before foaling

The first critical period occurs before the mare is due to foal. Nutritional requirements should be met in the last trimester that allow for the accelerated growth of the fetus that occurs during this time, and presents the mare in a fit, not fat, condition at foaling. Particular attention should also be paid to her teeth and feet and she should receive a de-wormer close to foaling. In the last 4 weeks of the pregnancy the mare should receive a booster vaccination against tetanus and any stitches in her vulva should be opened well in advance of her due date. Things to look out for during this period include premature lactation (bagging up or running milk) or discharge from the vulva, both of which suggest infection or inflammation of the placenta. Infection of the placenta results in a decreased supply of oxygen and nutrients to the fetus and may precede the birth of a weak or infected foal. An infected placenta, may become thickened, and be more likely to be retained in the uterus, resulting in complications for the mare. The thickness of the placenta can be evaluated by ultrasound by your veterinary surgeon in the late stages of pregnancy if there is concern.

Critical period 2: The birth

The next critical period is the birth itself. Once stage 2 labour begins (with the breaking of water) strenuous contractions should produce a foal on the ground within 30 minutes. If the foaling is difficult, internal damage such as tearing or bleeding may occur but this may not be evident from the outside. A red bag delivery is a red flag providing evidence of infection or inflammation of the placenta that caused it to partially separate from the wall of the uterus prior to foaling. When complications occur during the birth of a foal, veterinary attention should be sought right away. Mares, unlike cows, are relatively fragile and minor damage can result in long-term fertility problems.

Critical period 3: The first three hours

The first three hours after birth are the next critical period, during which the mare and foal establish an extra-uterine bond. If the foal fails to rise and nurse and thus stimulate oxytocin release in the mare, the mare may not pass her placenta in the normal time. Retention of the placenta may also occur if the placenta is inflamed or infected, so a red-bag delivery may precede a retained placenta. In some mares, there is no indication as to why they retain the placenta. Often when a piece of the placenta is retained, it is the tip of the part of the placenta that was attached to the non-pregnant horn or the uterus that is retained, so it is worth knowing to look for this. A retained placenta is an emergency as the tissue left inside becomes infected and rots, releasing toxins into the blood stream. The placenta should never be forcibly removed, as leaving even small strands of tissue inside the uterus can lead to severe infection and toxemia. One of the most life-threatening consequences of a retained placenta and toxemia is the development of severe laminitis, which may necessitate the humane euthanasia of the mare. The best solution is to tie up the ends of the placenta so the mare doesn’t stand on them and get prompt veterinary attention.

Critical period 4: First days after foaling

The next critical period is the few days after foaling when the consequences of the birth becomes obvious. The manner of the mare should be carefully observed in the day or two after she foals. Mares with internal infection, trauma or haemorrhage may be particularly quiet, off their feed or disinterested in the foal. Mild to moderate colic may be another sign of complications.

Washing out or douching a normal mare post foaling is not usually necessary. Mares will pass discharge from the uterus for a couple of days after they foal and this is normal as the uterus returns to a normal size ready for rebreeding. You will see brownish liquid passed along with her urine during this time. The process by which the uterus, which was capable of housing a 50kg foal, returns to a tube with about a 6cm diameter, is called involution. Oxytocin release, stimulated by frequent nursing by the foal, encourages involution and muscular contraction of the wall of the uterus to expel fluid and inflammatory debris left over from the foaling. Moderate exercise also encourages the expulsion of this fluid from the uterus.

Routine washing out of normal mares is not recommended for a number of reasons: firstly, anything that is passed through the cervix, including the flushing tube, may contaminate the uterus and set up inflammation and infection, and secondly, any blood clots that may have formed as a result of bleeding may be dislodged resulting in haemorrhage that may occasionally be fatal.

Some mares will, however, need assistance in the form of washing out or drugs to contract the uterus, to help clear this fluid from the uterus after birth. Mares that need to be housed for any reason, for example, if the foal requires a lot of attention, may require assistance, as their level of exercise is restricted. Mares that retain their cleanings will also require assistance. As a rule of thumb if the brownish discharge is still present at three days after birth, or if the discharge develops a foul smell, veterinary attention should be sought, as the mare may have developed infection in the uterus. Tetanus is another concern for these mares as these bacteria like to live in this rotten environment.

Stitches should be replaced in mares that require stitching and this is best done a few days after foaling. Anything that raises the blood pressure of the mare, such as the application of a twitch, should be avoided in the immediate day or two after foaling, to avoid the risk of dislodging clots and possibly fatal haemorrhage. If the site of previous stitching is infected or inflamed this should be allowed settle down as the surgery won’t hold otherwise. The mare can still be stitched before she is bred if necessary.

Getting the mare back in foal

When the birth appears to be uncomplicated, plans to get the mare back in foal often proceed right away. Many breeders, particularly TB breeders, will be hoping to get the mare back in foal as quickly as possible. The reproductive tract in the mare returns to normal function very quickly after she foals. So effective is this mechanism that mares may be ready to go back in foal again by the time they come into their foal heat, one week after foaling. If the mare foals very early in the spring, she may have been under lights during late pregnancy; if this is the case, keep her under lights after foaling to prevent her going back into anoestrus. Hormonal drugs can also be used during this period, under veterinary advice, to regulate the transitional period cycle and encourage ovulation.

Breeding on the foal heat is possible, if no complications occurred during foaling, given a few prerequisites: a veterinary examination should be done on day 6 or 7 post foaling to determine whether a mare is suitable for breeding, and this should be done irrespective of whether the foaling was difficult or not. Internal trauma such as a cervical tear can occur, even when the foaling appeared normal, and covering a mare with such a defect, would be a waste of time and resources. The mare should be examined by a vet to establish whether there is any internal trauma, such as bruising or tearing to the vagina or cervix, or any evidence of delayed involution or infection of the tract. If these are present, they should be promptly treated and the mare should not be bred on her foal heat. In addition, mares that ovulate before 10 days post-partum are less likely to go in foal on that cycle than those whose first post-partum ovulation occurs after 10 days. That means if a mare is ready to be bred but ovulates on day 9 post foaling, she should not be bred on that cycle, but can be short cycled a week later and bred subsequently.

As with any breeding mare, minimising infection and inflammation in the reproductive tract is critical. Inflammation sets up a poor environment for the survival of sperm and/or embryo. The more times a mare is cross-covered in a heat cycle, the more inflamed her uterus will be. So appropriate teasing, and a timely veterinary examination to pinpoint the most appropriate time for cover, saves time and resources in the long run. Also strict attention should be paid to breeding hygiene and reference to the Codes of Practice in regard to the transmission of contagious diseases.