by Angela Smith BVSc
Prior to foaling. One of the first signs is the distended udder. During the last month the udder usually enlarges. The mare’s udder may fill up at night while she is resting and shrink during the day while she exercises. When the udder remains full through out the day, then foaling is probably imminent. The mare should be watched closely.
Filling of the teats as the udder enlarges.The upper portion of the teat is stretched in a manner that is difficult to distinguish it from the rest of the udder. The lower portion of the teat remains small, but as foaling gets nearer the teat enlarges and is reflected outward by the increasing pressure from within the udder.
Relaxation of the muscles of the pelvic area. Relaxation of this region usually occurs about 3 weeks prior to foaling. These changes allow the foetus to pass through the birth canal with greater ease. This process is gradual and may not be seen on all mares but in most, a distinctive change in the appearance can be seen. A hollow develops on either side of the root of the tail as muscles of the hip and buttock area start to relax. This area can be examined each day when the mare is checked. The abdomen becomes increasingly pendulous as it enlarges and about a week prior to foaling it may appear to shrink as the foal shifts into position in preparation for foaling. This change is not always seen in all mares.
Waxing. When wax like beads appear at the end of each teat ( they are droplets of colostrum ). They can appear anywhere between 12-36 hours prior to foaling or a week or two before foaling, and sometimes fails to occur in some mares. So this not a reliable method of predicting foaling occurrence as it can be so variable between individual mares.
Relaxation of the vulva Within the last 24-48 hours before foaling the mares vulva can be observed to swell and relax in preparation to stretching several times its normal size to allow passage of the foal.
Milk flow Appearance of wax on the end of the teats can also be accompanied by droplets of milk. Although wax and milk secretion usually indicate delivery will occur very soon, many mares foal without either . While some mares drip or stream milk for several days prior to foaling. Unfortunately, mares that stream milk prior to foaling lose large amounts of colostrum, the vital first milk that contains antibodies and a laxative for the newborn foal. Mares showing spontaneous milk flow should be closely watched , not only for the onset of foaling but also to determine how much colostrum is lost during this period. If the mare is losing a significant quantity it should be collected and frozen. Colostrum can be thawed and fed to the new born foal at birth.
Restlessness Many mares exhibit behaviour changes. During the last few weeks of gestation a mare can become cranky, restless and as she enters the first stage of labour, the mare usually wants to be left alone. She may walk continually in pasture or stall, switch her tail, look at her sides, kick at her abdomen. These signs are also indicative of colic, but if the mare eats, drinks, defecates, urinates frequently, then the first stage of labour is probably in progress.
Sweating As labour approaches the mare often breaks into a sweat. The mare’s neck, flanks, may feel warm and damp or a general sweat over all the body may occur.
Parturition, or the process of foaling.
The progression of the physical changes that occur in foaling are divided in to three distinct stages.
- stage one - positioning of the foal
- stage two - delivery of the foal
- stage three - expulsion of the placenta
The ability to recognise each stage and to follow the normal chain of events that occur during each phase allows the attendant of the mare to be able to assess whether that mare needs assistance; to be able to recognise if the second or third stage of labour is delayed or altered in some way from the normal expectations. Fortunately ~ 90% of mares foal normally.
This is when the foetus gradually shifts from a position on its back, rotating until its head and forelimbs are extended in the birth canal. The outward signs are: restlessness, sweating of the flanks, as the uterine contractions become more severe the mare may become very nervous, pacing, walking fence lines, looking at her flanks, kicking at her abdomen, she may paw the ground, may even get up and down several times to help position the foal. Pastured mares usually move away from other mares and may seek an isolated corner of the paddock. While some mares show few signs during this stage others show marked distress for several hours. Transitory contractions that occur without cervical dilatation cause the mare to show signs of distress then " cool off " several times before the foal actually moves into the birth canal. Once these signs are recognised the attendant should check the mare then observe from a discreet distance.
The end of the first stage is marked by rupture of the allantoic membrane and a sudden release of allantoic fluid. A process that helps lubricate the birth canal. This usually occurs 1-4 hours after the onset of the first stage.
Delivery of the foal 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 someone should catch the foal and lower it to the ground gently to help it avoiding injury. If the mare should lie down next to a wall or a fence the attendant should make sure there is plenty of room for the foal’s delivery. If the mare is too close to an obstacle the mare should be made to get up and allowed to find a new position, where the perineal region is free.
The foal is normally presented in an upright position, with its head tucked between extended forelegs. (This is the time the attendant usually checks the foal’s position by inserting an arm into the mare's vagina after she breaks water. This should be done with a sterile gloved arm or after the arms are suitably scrubbed thoroughly in the appropriate antiseptic solution). As the head and neck appear, enclosed in the bluish-white amnion, the foal’s shoulders pass through the pelvic opening. One foot is usually positioned slightly in front of the other to help reduce the circumference of the foal’s shoulder and there-by ease its passage through the birth canal. After this critical period the mare usually rests for a short time then delivers the rest of the foal with relative ease. 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 the attendant should tear the membrane to clear the nasal passages so the foal can breathe and so as to prevent suffocation of the foal.
After the foal’s hips have passed through the mare’s pelvis the mare usually rests once more. The foal’s hindlegs may remain in the mare’s vagina for several minutes, in this time it allows the foal to receive essential blood from the placenta via the umbilical cord and should not be interrupted. In most cases, the time from rupture of the allantochorion to the post delivery rest period is completed in minutes, but a range of 10 to 60 minutes is considered normal. As the mare rises or as the foal struggles to stand, the umbilical cord usually breaks. Because the foal receives a significant amount of blood from the placenta via the umbilical cord, the cord should not be prematurely ruptured.
Expulsion of the placenta is the last stage of labour. This usually occurs within three hours. However the normal range is 10 minutes to 8 hours. During this period the uterine contractions continue to proceed in an effort to expel the placenta. The mare will exhibit signs of discomfort. The placenta is expelled inside out because the contractions cause inversion of the placenta as it comes away from the lining of the uterus. The purpose of these contractions is also to cleanse the uterus of fluid, debris and return the expanded uterus to its normal size.
As this stage may last several hours it may be helpful for the attendant to tie the afterbirth in a knot that hangs above the mares hocks. This will help prevent the mare from stepping on the membranes and tearing them out prematurely but also adds gentle pressure using gravity to aid in expelling the placenta. The attendant should not attempt to pull the placenta from the mare’s reproductive tract as this could cause tears and leave remnants of placenta that could cause future uterine infections. Retention of even small pieces of placenta is a potentially very serious condition. Once the placenta is passed it is a good policy to lay it flat on the ground and check it is all intact. There is new evidence that suggests that the weight of the placenta correlates to the condition of the mares reproductive tract and also correlates to the health of the foal. The normal placental weight in light horses is 10 to 13 pounds or the equivalent in kgs. The texture of the membrane is important. If the membrane is thick and tough or if it shows haemorrhagic spots, then placental infection might be suspected. When the placenta has been infected the foal will often show some abnormality at birth. Close examination of the placenta is important, if you have any doubts keep the placenta in a plastic lined and covered bucket with a small amount of water to keep moist till your veterinarian can examine it. The amnion has a translucent white appearance, while the allantochorion is normally red and velvety on one side and light coloured on the other. The placental membranes consist of the amnion that encloses the emerging foal and the allantochorion.
Sometimes brown bodies of putty like consistency can be found when examining the placenta; they can also sometimes be expelled when the mare’s waters break. These are harmless remnants that are believed to originate from minerals and proteins deposited in the allantoic cavity during gestation.
So in summary the following points should be noted and recorded by the attendant about the placenta.
- The time required to expel the placenta after the foal’s birth.
- Absence of any pieces ( this can simply be checked by filling the allantochorion with water to check for holes or tears).
- The condition of the membranes, (weight, colour, thickness, and presence of any haemorrhagic spots).
Occasionally the mare can show signs of colic after the third stage of labour is complete. If the pains caused by cramping of the empty uterus are severe in the mare, veterinary attention may be required to relieve her discomfort during this adjustment period.
The mare should be watched carefully for 4 to 5 days after foaling. It is normal for the mare to have a dark red discharge for 6 to 7 days, but if a yellow discharge is seen this indicates infection. This requires veterinary attention.