What to expect when your mare is “expecting”

Dr. Christine Bartley

This guide is intended for mare owners and farm attendants who will be attending a foaling, to help familiarize them with the process. This is not meant to guide the diagnosis or treatment of problems in a foaling mare, as this should be done with the help of your veterinarian. My goal is for this to help prepare and serve as a reference for a typical equine parturition. This guide is based on my experience attending hundreds of Thoroughbred foalings in central Kentucky. In the event of an emergency, please contact your veterinarian.

Prior to foaling:

• Mammary gland development aka “bagging up” occurs 4-6 weeks prior to foaling
  • Any mare that develops an udder sooner than this time period should be evaluated by a veterinarian: may be an indication of placentitis, twins, or fetal stress
• Prepare the mare’s foaling area 4-6 weeks prior to due date (340 days from ovulation): heavily bed down stalls (I prefer straw and to the mare’s mid-cannon) and be aware of what they are grazing
  • Fescue toxicity: endophytes in fescue grass act as dopamine receptor agonists which can cause a whole slew of issues, most commonly: prolonged gestation, red bag delivery (an emergency), and decreased milk production due to low circulating prolactin – ideally remove from this forage source 90 days prior to foaling & discuss with veterinarian treating with Domperidone (a dopamine antagonist). Pasture can be tested for fescue, but some will choose to dry lot in the last month of gestation to avoid this issue.
• Pre-foaling vaccinations: regionally dependent. Should occur @ 10 months gestation for appropriate passive transfer in colostrum (the first milk the foal will drink which provides immune protection and antibodies).
• Antibody screen for any evidence of antibodies against other blood types in the horse. This should be performed approximately 2 weeks before the due date and helps identify if the mare’s milk could have detrimental effects on the foal. Neonatal isoerythrolysis (NI) occurs when the newborn ingests milk containing antibodies to its own blood type. This can be fatal and this blood test will help identify if the mare is at risk for producing potentially harmful colostrum.
• If the mare had a Caslick’s procedure performed to prevent contamination during gestation, this will need to be opened prior to foaling. Usually this is done at the same time as the antibody screen.
• As the mare approaches foaling, you will notice some changes as her body begins to prepare for the delivery:
  • Physical changes to the mare: relaxation of pelvic ligaments and vulva. The mare may develop a ventral plaque of edema as well due to hormonal changes and impact of heavy gestation on lymphatics.
  • “Waxing”: thick, candle-wax-looking secretions forming at the end of each teat occur 6-24 HOURS prior to foaling
  • There are many ways to predict foaling:
    • measure milk calcium/potassium concentrations (my preferred method – serially collecting samples of milk in red top tube and running a “milk electrolytes” test at RREH – costs $29 per test – when changes occur to electrolytes predicts foaling within 24-72 hours), also foal watch monitors (magnetic device sewed in to vulvar lips and connected to cell phone – when water breaks, it sends an alarm), milk test strips for pH of milk, etc

Supplies to have on hand:

• Brown gauze for tail wrap
• Bucket with cotton and warm water – for washing udder
• Clean towels – to vigorously rub new foal
• Baling twine for fetal membranes
• Heavy duty trash bag for fetal membranes
• Dilute iodine for umbilical care

Stages of Foaling:

• Stage 1 labor:

  • may last from 30 minutes up to 6 hours. In some mares they can start and stop stage 1 labor. This stage is when the mare’s uterus begins more coordinated contractions and the fetus changes position so that it goes from lying on its back to being in the normal “diving” position with front legs and head and neck extended.
    • The mare will demonstrate restlessness, tail swishing, mild colic, sweating, “veined up,” stretching, may spontaneously drip or spew milk
    • It can be hard, but you MUST differentiate between labor and colic – do NOT give Banamine or other pain control medications without consulting a veterinarian
    • Fetus is reorienting itself – mare may lay down and get up multiple times – please allow this to happen. Keep lights off and spectators quiet
    • Cervix is dilating during this stage
    • Stage 1 labor ends with rupture of chorioallantois “breaking water”

• Stage 2 labor: < 40 minutes

  • Multiparous mares, or mares that have had foals before, may give birth quickly, in about 10 minutes. I am comfortable with the girls, who are maidens, taking up to 40 minutes to expel the fetus. MAKE NOTE OF WHAT TIME SHE BREAKS WATER in order to accurately determine, down to the minute, if she’s taking longer than expected, which may indicate a problem.
  • Stage 2 labor begins with the breaking of water and ends with the passing of the fetus
  • Mare may still get up and down and experience forceful abdominal contractions, but she should lay down for the actual birth. If she does not feel comfortable lying down, in my experience, it is almost always because there is too much human intervention. Stay quiet, stay out of the way.
  • Begin to see amnion covered front limbs and head coming through the vulva. The amnion is a pale membrane of varying opacity. If you see a red bubble coming out, this is not normal and is most likely a “red bag,” which I will describe later.
  • Stage 2 labor ends with the expulsion of fetus

• Stage 3 labor: < 3 hours

  • Begins when foal is delivered. Please keep record of time foal is delivered.
  • Mild colic signs due to uterine contractions
  • Ends with passage of fetal membranes, aka placenta

FOALING EMERGENCIES!!

• “Red bag” or in scientific terms, premature placental separation. The chorion is the red velvety surface of the placenta that attaches to the uterus. This is normally broken at the cervix in a normal delivery and then the foal’s feet surrounded by amnion protrude through the birth canal. When there is an abnormality in the placenta and this membrane separates from the uterus early, or is too thick to be broken, the foal pulls this with it as it exits the birth canal. It will appear as a red velvety surface like a bubble and no fluid is released as the mare has not “broken her water.” Because this surface is not detaching from the uterus, the foal loses the healthy blood supply and oxygen, causing this to be an emergency. When the red bag appears, rupture of the membrane and delivery of the foal must be facilitated promptly. You must manually rupture the membrane and assist the foal’s delivery to ensure the foal can get oxygen.
• Dystocia: difficult or prolonged foaling. The foal should come out with head resting on top of front legs. Advances should be evident every 5-10 minutes after the mares’ water breaks and the foal should be delivered within ~30 minutes. Postural abnormalities are most common – neck/head/limb flexions. If progress is not being made, or the presentation of the foal is abnormal (tail or hind legs first) – MUST refer to hospital for general anesthesia/manual extraction OR cesarean section. No time to waste and early intervention is crucial – the decision to refer must be made quickly to save both foal and mare.

POSTPARTUM MARE EMERGENCIES:

• Retained fetal membranes/placenta: placenta is considered “retained” if the mare has not expelled it within 3 hours after parturition. If the membranes are retained for longer than 6 hours, significant complications can occur for the mare, like sepsis, laminitis, and death so attention to this part of the birthing process is very important. Membranes should be knotted up (difficult and slippery) or tied at or above the level of the hock with baling twine (easier) to prevent the mare from stepping on it. Please SAVE THE PLACENTA by storing it in a heavy-duty garbage bag so it can be examined by your veterinarian. Even if it appears to pass normally and in one piece, a small area can still be retained, and your veterinarian will carefully examine both horns to make sure it is complete. Even a small amount of placenta retained in the uterus is enough to make a mare sick. This cannot wait until morning to alert your veterinarian – manual retraction of the retained portion is indicated followed by uterine lavage with lactated ringers’ solution. Antibiotics are also often started.
• Postpartum Hemorrhage: colic signs, pale mucous membranes, weakness. More common in older mare who have degenerative changes within vascular walls but can occur in any mares, especially with a difficult parturition. Call your veterinarian immediately if you suspect your mare is bleeding – you will likely NOT see evidence of blood outside the mare. She will be bleeding into her uterus, broad ligament, or abdomen – so clinical signs are the only sign. Your veterinarian will administer IV and oral clotting agents as well as multiple pain control medications. Your goal in the meantime is to keep her quiet and as calm as possible (lights off in the stall, etc).

Postpartum mare & foal care:

• DO NOT CUT the umbilical cord. The umbilical cord will break naturally as the mare stands up after foaling. In a bind, the umbilical cord should be pulled/ripped near the attachment to the foal, never severed with a knife or scissors – but best-case scenario it will tear on its own. The umbilical stalk should be dipped in a dilute iodine solution (weak tea appearance) shortly after it is broken to deter bacteria.
• A good rule of thumb for the foal’s progression after birth is “Stand by 1 hour, nurse by 2 hours, pass placenta by 3 hours.” This is approximately the time it takes for a foal to figure out standing and nursing. While we hope that this happens quickly, this is NOT a middle of the night emergency for you to call your veterinarian. The closure of the gut happens at approximately 12 hours in the foal so we will need to get her a source of colostrum prior to 12 hours of life. A veterinarian will come by first thing in the morning to pass a tiny NG tube and administer colostrum to its stomach if the foal has not nursed on its own yet. Concerning signs in the neonatal foal are abnormal mentation, circling, and persistent rolling. It is also good to watch for the first feces being passed and normal urination.
• First day of life: I recommend a “new foal exam” be performed on the new foal the first day of life. This includes an eye exam (congenital cataracts, entropions, hydration status), check for cleft palate, heart and lung auscultation (murmurs, aspiration pneumonia), rib palpation (VERY IMPORTANT as ribs can easily break during the passage through the birth canal. While most heal fine on their own with stall rest, it is important to determine if your foal has broken ribs because when severe, the edges are capable of puncturing vital organs). Legs will also be examined at this time on a flat surface to determine if turnout is acceptable or if she would benefit from stall rest until tendons strengthen. I also recommend a basic bloodwork panel (CBC plus IgG) to determine if underlying infection and if passive transfer of antibodies has been successful.
• Should you administer plasma to your foal?? Many farms administer one liter of hyperimmune plasma to the foal intravenously during the first day of life. The plasma I recommend is taken from mares vaccinated for common diseases affecting foals – Clostridium, Rhodococcus, and rotavirus. I do see a benefit with this later in the foals’ life – it does not prevent these diseases but in many cases, it lessens the severity of the disease. In 2020, the cost to the client was $375/liter. Hyperimmune plasma is also the treatment for a foal who has failure of passive transfer (has not adequately absorbed antibodies from the mother’s milk), in this case, it is not optional. Using it as an antibody boost is completely up to you but please let me know what you decide so I am able to order ahead.
• Please take the temperature of the foal EVERY DAY, TWICE A DAY and WEAR GLOVES WHEN HANDLING THE FOAL and alert your veterinarian if the temperature is >102.5 – early intervention of diseases is key for the neonate. Plus, frequent handling is excellent for the young foal and will make them easier to deal with as they age!
• I recommend evaluating the mare by rectal palpation and ultrasound as well as a vaginal exam on at 7 days post foaling EVEN IF you do not intend to breed the mare back the following year. This helps us determine if she is involuting well, if she is carrying abnormal fluid in the uterus, if she has bled during parturition, if she has major cervical or vaginal tears, etc. Please also take your mare’s temperature once a day for the first week after foaling and call your veterinarian if it is >101. Monitor the vaginal discharge as well and alert your veterinarian if it is foul smelling or copious amounts or frank blood.
• Please discuss regular foal physical examinations with your veterinarian. Screening and disease prevention is much easier than getting behind the disease process.