You’ve had all the pregnancy scans, waited 11 months, now its time for foaling. What’s normal?
Parturition in the mare is a very rapid process that occurs in three steps.
1. Preparation stage
This is the hours or days before birth when the mare is displaying restless behavior. You may note her appearing ‘colicky’. Commonly we see mares seeming unable to get comfortable, pacing, frequently urinating or sweating. This period usually lasts approximately an hour but it is not uncommon for mares to show signs of parturition days out from actually foaling. During this stage, the foal is rotating within the uterus and getting into the appropriate position for a normal delivery.
2. Active foaling
Stage 2 begins with the rupture of the chorioallantois and release of the allantoic fluid (ie. Breaking of the waters). From this occurring to the foal being born should last no more than 30mins. In a normal foaling, you will see both front feet slightly staggered, closely followed by the head. At this stage the foal is still held within the amnion, a clear/white coloured membrane.
3. Delivery of the foetal membranes
Expulsion of the foetal membranes is considered normal if it occurs within three hours of birth of the foal. It is recommended that the membranes are examined closely once they are delivered to ensure they are whole and no ‘tags’ are left within the uterus. The membranes should also be examined for grossly for any signs of placentitis (thickening, discolouration or exudate) as this could impact management of the foal going forward.
Premature placental separation aka red bag
The equine placenta has 2 components; the chorioallantois and the amnion. The chorioallantois attaches to the wall of the uterus by millions of microscopic connections called microcotyledons. The amnion is the membrane which surrounds the foal.
During stage 2 of a normal foaling, the chorioallantois ruptures at the point of the cervix, releasing the amniotic fluid and the amnion, a whitish/grey membrane should protrude through the vulva. However, occasionally, the chorioallantois prematurely separates from the uterine wall and the entire placental unit protrudes through the vulva. The chorioallantois has a distinct red, velvety appearance. This is considered an emergency as the foals’ oxygen supply has been disrupted, and as a consequence the foal may die from asphyxiation or suffer from hypoxic related brain injury. If you see a red membrane during your mares foaling, please call the clinic immediately for advice.
Dystocia
Dystocia, or ‘difficult birth’ is a relatively uncommon problem in mares. However, if your mare has been in active labour, ie. Has expelled her amniotic fluid but has failed to deliver a foal within 30 minutes, you should contact the clinic. The most common cause of dystocia in horses is due to incorrect position of the foal within the birth canal. Sometimes this can be corrected simply on farm, but sometimes may require a general anaesthetic and/or caesaean.
Retained foetal membranes
After the birth of the foal, it is normal for the mare to expel her membranes within 3hrs. If your mare has not delivered her membranes within 6hrs of birth, it is important to contact us and organise a visit in order to remove them. If left in place, mares quickly become systemically unwell and may develop metritis- endotoxaemia-laminitis complex. Retained foetal membranes are much more likely to occur following placentitis, dystocias or abortions.
Failure of passive transfer
Neonatal foals enter the world without any antibody protection against disease. As such, foals are completely reliant on absorbing antibodies through the mares’ colostrum. Colostrum is antibody rich milk that is produced by the mare in the last 1-2 weeks of pregnancy. The foal is able to absorb antibodies from the milk and transfer them into the blood stream. This process is most effective for the first 6-8hrs and but stops by 24hrs old.
This colostrum is crucial to prevent the foal, in the early stages of life from developing life threating infections such as pneumonia, septicemia and septic arthritis. If you’re concerned that your foal has not ingested any/enough colostrum, we recommend contacting the clinic for advice regarding diagnosis and treatment.
