Mares have a long gestation period, with the average pregnancy lasting between 335 to 350 days or roughly 11 months. However, gestations can last anywhere between 320 to 360 days, so being able to recognise the signs that a mare is nearing her foaling date can prove invaluable.
As your mare approaches the end of her gestation period, it’s important to be vigilant for changes that indicate foaling is near. Recognising these signs while remembering that each mare is an individual and may behave slightly differently ensures you can make necessary arrangements and provide appropriate care during the birthing process.
Did you know?
Many different factors can influence gestation length, including the mare’s age, previous pregnancies, foetal sex, genetics, and season. Because of this, and the fact that all mares respond as individuals to the demands of pregnancy, accurately predicting the exact foaling date for your mare can be challenging.
There is no foolproof method to predict in advance when your mare will go into labour but here we look at some of the key indicators that a mare is getting close to her foaling date:
Changes in the udder and teats
When a foal is first born, they are entirely reliant on colostrum and milk from their mother to provide all of their nutrition. During pregnancy, the mare’s mammary glands go through several changes to prepare the mare for lactation post-foaling.
As early as 4 to 6 weeks prior to foaling down, you may notice your mare’s udder hardening and appearing fuller. Enlargement of the udder is most noticeable in the last two weeks before giving birth and is commonly referred to as ‘bagging up’. This fullness is a result of mammary tissues in the udder beginning to produce milk. As the expected foaling date approaches, the two halves of the udders will further fill with milk and feel firmer to the touch. The udders may look more boxy, with the crease between the two halves becoming less pronounced.
As the mare gets closer to parturition, the udder will continue to fill with milk. Pressure within the mammary gland increases, causing the teats to become distended or enlarged. This enlargement ensures that the foal is able to latch on properly and efficiently extract the vital colostrum and subsequent milk. While the exact timing can vary among individual mares, filling of the teats typically occurs two to seven days before foaling.
Waxing refers to the formation of small, waxy, yellowish beads at the end of a mare’s teats. This substance is thickened colostrum, the mare’s first milk, which is rich in antibodies and other essential nutrients. As parturition approaches, the mare’s mammary glands start producing colostrum. When the pressure within the udder increases due to the accumulation of this colostrum, small amounts may leak out and dry on the teats, forming a waxy substance that looks like hardened milk droplets. Between 70 – 95% of mares develop waxing on the teats before foaling. This sign is most common within 6 – 48 hours prior to foaling, but can occur as early as two weeks before foaling or not at all.
Within a few hours of foaling, your mare’s teats may begin dripping or streaming milk, due to increased pressure in the teats causing the colostrum to leak out. Keep note of how long this streaming occurs, especially if a large amount of colostrum is lost. In these cases, it may be necessary to supplement the foal with colostrum to ensure they receive adequate nutrition and to support passive transfer of immunity
Relaxation of the pelvic muscles and tailhead
As the time for foaling nears, mares undergo various physiological changes to ensure a smooth birthing process. One of the most prominent of these changes is relaxation or softening of the pelvic area. The hormone relaxin plays an important role in this process. Produced in significant amounts during late pregnancy, relaxin helps relax muscles in the uterus and pelvic ligaments to facilitate passage of the foal through the birth canal.
Additional changes observed prior to foaling include:
- Relaxation of the pelvic ligaments around the croup.
- Softening of the muscles surrounding the tail, resulting in little resistance when moving the tail.
Did you know?
Maiden mares experiencing their first pregnancy, may not follow a typical timeline. They need close attention throughout the gestation period to ensure a healthy delivery.
Abdominal shape changes
Another sign that foaling is imminent is a noticeable change in the mare’s belly contour. This is caused by the foal moving into the proper birthing position within the uterus. The mare’s belly will drop as the abdominal muscles relax, and a prominent point will form. Some mares carry their foal off to one side throughout gestation, but the abdomen tends to become more symmetrical as foaling approaches.
Changes in vulva appearance and secretions
As foaling approaches, the mare’s vulva and perineal area becomes more relaxed and elongated. There may be slight swelling, and some mares will have clear, thin secretions from the vulva. Elongation of the vulva, potentially accompanied by these secretions, generally suggests 24 – 48 hours until foaling.
Behavioural changes
Some mares exhibit behavioural changes as foaling approaches. If the mare begins to isolate herself from other horses or spends a lot of time standing quietly or lying down, it could be a sign of foaling preparations.
In the final 24 hours, mares often become increasingly restless. She may frequently switch from lying down to standing up, pace the stable, urinate, or seem generally anxious. She may paw at bedding, turn in circles, or attempt to create a comfortable spot for foaling. She might lose her appetite and also bite or kick at her sides, and show other signs of mild colic which often indicates labour is imminent.
Temperature fluctuations and sweating
Fluctuations in a mare’s body temperature can be used to reliably predict the onset of parturition. Research shows that average body temperature decreases by 0.3°C on the day of foaling compared to the five preceding days. A larger temperature drop may be a better indicator of impending labour. According to research, if you see a drop of 0.5°C or more, there’s a greater than 95% chance the a mare will foal within the next 12 hours. However, not all mares follow this pattern. One research report describes an increase in temperature 90 minutes prior to foaling.
Did you know?
If you are interested in using temperature changes to predict foaling, it is essential to measure your mare’s temperature regularly and at the same time of day to establish their average body temperature.
Creating the best foaling environment
When the signs indicate that foaling is imminent, a quiet, clean, and safe environment is essential. Consider moving the mare to a designated foaling stall with straw bedding to minimise bacterial exposure. Having foaling equipment on hand, including clean towels, iodine for the foal’s umbilical stump, and your vet’s contact information, can make a significant difference if assistance is needed.
Final thoughts
Being attentive to these signs helps create a smooth and safe foaling experience for your mare.