The three stages of parturition in horses

The three stages of parturition in horses

When foaling a mare down it is important to recognise each stage of the foaling process during parturition, and be able to assess whether the mare needs assistance or intervention. Whilst 90% of mares foal in a manner that would be considered normal, it is particularly important to be able to recognise if the second or third stage of labour is delayed or altered in some way from the normal expectations. Often early recognition that the process is not going to plan enables action to be taken swiftly, with the mare and foal then given the best chance of survival. 

The physical process that occurs during foaling can be divided into three distinct stages: 

1. stage one – positioning of the foal 
2. stage two – delivery of the foal 
3. stage three – the expulsion of the placenta 

Stage One 

Stage one involves the foetus gradually shifting from a position on its back, it rotates until its head and forelimbs are extended in the birth canal. During this stage it is normal for the mare to show signs of restlessness and sweating of the flanks. As contractions become more severe, the mare may become unsettled, pace, or walk fence lines. A mare may also look at her flanks, kick at her abdomen, and she may paw the ground in signs that would normally be seen with colic. It is also normal for a mare to get up and down several times to help position the foal. Mares out in paddocks usually move away from other mares and may seek an isolated corner of the paddock. The variation of signs shown at this stage can vary from mare to mare, some show few signs during this stage, whilst others show signs for several hours. It is always preferable to observe the mare from a discreet distance during this stage of foaling, as it is an instinct for the mare to wish to place herself as far from other horses or people as possible. 

The conclusion of the first stage of parturition is marked by the rupture of the allantois membrane, which results in a sudden release of fluid, this process helps lubricate the birth canal. This usually occurs 1-4 hours after the onset of the first stage. 

Stage Two 

The second stand involves the delivery of the foal. It is characterised by very strong contractions of the abdominal and uterine muscles. During this period the mare usually positions herself on her side with her legs fully extended to facilitate voluntary straining that aids her expulsion efforts. She may get up and down several times to help position the foal or may even move around with the foal’s head and legs protruding. If labour continues while the mare is standing, catch the foal whilst it’s being expelled and lower it to the ground gently. If the mare is too close to an obstacle, she should be made to get up and allowed to find a new position where there is sufficient room for the foal to be expelled. 

Normal foal presentation involves the foal presenting in an upright position, with its head tucked between extended forelegs. The head and neck should appear next (enclosed in the bluish-white amnion) and then foal’s shoulders should pass through the pelvic opening. After the foals shoulders have passed the mare usually rests for a short period and then delivers the rest of the foal. 

The amnionic foetal membranes are usually broken as the foal emerges or as it first attempts to lift its head. If the membrane is not broken immediately after the foal’s delivery, it is vital to intervene and tear the membrane to clear the nasal passages so the foal can breathe, otherwise the foal is at risk of suffocation. 

Following the foal’s hips passing through the mare’s pelvis, the mare may decide to rest once more. It is normal for the foal’s hindlegs to remain in the mare’s vagina for several minutes. This time allows the foal to receive the last of the essential blood from the placenta via the umbilical cord. This process of expelling the foal should normally range from 10 to 60 minutes. As the mare rises or as the foal struggles to stand the umbilical cord usually breaks, it is important not to intervene and break the cord until this occurs. 

Stage Three 

This final stage involves the expulsion of the placenta. This usually occurs within three hours of the foal being expelled. However, the range in which is considered normal varies from 10 minutes to 8 hours post foaling. During this period the uterine contractions continue aiding in the expulsion of the placenta. It is normal for the mare to exhibit some signs of discomfort during this stage. 

The placenta is expelled inside out due to inversion of the placenta as it comes away from the lining of the uterus. The contractions also help to cleanse the uterus of fluid, debris and return the expanded uterus to its normal size. 

It is normal for this final stage to last several hours. Retention of pieces of placenta can pose a very serious risk, so once the placenta is passed it is important to lay it flat on the ground and check it is all intact. It is also important to check the texture of the membrane. If the membrane is thick and tough or if it shows haemorrhagic spots, then placental infection may be suspected. If you notice any abnormalities or have any doubts, place the placenta in a plastic bucket with a small amount of water to keep it moist until your veterinarian can examine it. 

After foaling, the mare should be watched carefully for at least 4 to 5 days. It is normal for the mare to have red discharge for 6 to 7 days; yellow discharge would indicate an infection. It is also a good idea to have a post foaling check carried out on the mare and foal by your veterinarian to ensure that both are healthy and there are no abnormalities that you may have missed.