Proactive care tips for mares

Jacquelin Boggs, DVM, MS, DACVIM 


Waiting on a new foal to arrive is an exciting time! On average, a mare’s pregnancy lasts between 320-360 days (median of 340)—almost a year after breeding. Now is a great time to check in with your veterinarian to keep preventive health care top of mind for your mare and her developing foal.

Update core and risk-based vaccinations

Your mare passes immunity on to her foal through the colostrum (the first milk rich in maternal antibodies). It is important to ensure your mare is properly vaccinated for diseases that could affect the foal during the last 4 to 6 weeks of her pregnancy.

  • The mare will develop antibodies and transmit them to her foal to protect the foal during the critical time before the foal’s immune system is fully developed.
  • The goal of vaccinating the mare is passively acquired immunity, which occurs when the newborn foal ingests colostrum. The foal ideally ingests the colostrum in the first several hours after birth.
  • The antibodies are ingested through the gut of the foal and will help protect the naïve neonate until she is capable of developing her own immune system.

Veterinarians are advised to follow the American Association of Equine Practitioners (AAEP) vaccination guidelines when making recommendations. You may find this chart to be a helpful resource.

  • The AAEP recommends vaccinating mares against the five core equine diseases annually and providing the vaccine(s) approximately one month prior to foaling.1 Core EQ Innovator® is the first and only vaccine to provide effective protection against all five core disease antigens in horses in a single dose.
    • Core EQ Innovator helps protect your horse against the five core (potentially fatal) equine diseases—rabies, tetanus, West Nile virus, Eastern and Western equine encephalitis. It is also labeled safe for use in pregnant mares during their third trimester.2
    • All antigens in Core EQ Innovator are backed by the Equine Immunization Support Guarantee to help provide you with peace of mind through unparalleled vaccination support.

It may also be necessary to vaccinate your expectant mare against risk-based diseases. Check with your veterinarian to see if your mare needs one or several of the following vaccinations:

  • Fluvac Innovator® EHV-4/1 aids in prevention of equine influenza and equine herpesvirus, also known as equine rhinopneumonitis (EHV-1 and EHV-4).
    • Equine influenza is one of the most common infectious diseases of the respiratory tract of horses. Most clinical signs are respiratory and may also include fever, edema and enlarged lymph nodes.
    • Equine influenza is highly contagious and capable traveling 150 feet through the air—meaning mares can be exposed to EIV across the distance of half a football field.3 It is transmitted via aerosol or direct contact with contaminated fomites from horse to horse and can survive on hands, clothing, brushes, buckets, stall walls, feed troughs, trailers and more.
    • Equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 (EHV-4) infect the respiratory tract, the clinical outcome of which can vary in severity from sub-clinical to severe respiratory disease, including fever, lethargy, anorexia, nasal discharge, cough, and/or mandibular lymphadenopathy. Both EHV-1 and EHV-4 spread primarily by the respiratory route, by direct and indirect (fomite) contact with nasal secretions or by contact with aborted fetuses, placental and fetal fluids, and the placenta.
  • Pneumabort-K® + 1B can help limit the risk of abortion caused by equine herpesvirus type 1 (EHV-1) at 5, 7 and 9 months of gestation.
  • Lepto EQ Innovator® protects against equine leptospirosis (Leptospira interrogans), which can present as abortion, equine recurrent uveitis or renal disease in broodmares.
    • Infection is acquired via exposure to contaminated water and soil. Leptospiral organisms can also shed into the urine and body fluids of infected animals (including wildlife hosts).4
  • Equine Rotavirus Vaccine* of pregnant mares provides passive transfer of antibodies to foals to protect against equine rotavirus, a viral diarrhea that affects foals. Infectivity and severity of this disease tends to decline as foals grow older.5
    • The best way to work towards protecting the foal is through vaccinating mares during gestation so that she can pass antibodies through the mare’s colostrum.
  • A botulism vaccine is recommended in certain parts of the country to protect against clostridium botulinum bacteria. Botulism can result from exposure to neurotoxins produced by soil-borne, spore-forming bacterium, Clostridium spp.6
    • Horses may show signs of muscle weakness that could progress to paralysis, an inability to swallow, and frequently, death.6

Maintain a regular deworming schedule

Parasites can negatively impact your mare’s health during the time when her system is busy supporting the developing foal. Deworming mares with Quest® Gel is recommended for use in the early grazing season around foaling (spring timing) and is safe for use in breeding and pregnant mares.7 Consult your veterinarian for assistance in the diagnosis, treatment, and control of parasitism.

Provide routine dental and hoof care

Although your mare may not be working at her previous riding or competition pace, it’s important to provide the same routine care, including regular farrier visits. If she wears shoes, talk with your farrier and veterinarian about when or if to pull them to avoid injury to the newborn foal.

Also, a friendly reminder to schedule your mare’s annual dental appointment, as correcting any dental issues ensures that she gets the most nutrition out of the food she shares with her developing foal.

Begin planning for your foal’s arrival

It's important to know your mare's breeding and/or foaling date as well as her gestation time frame. Typically speaking, a mare can foal early or up to 12 days after the expected due date. Now is a good time to proactively plan where your mare will deliver, especially in case of an early arrival.

If foaling at home, a clean grassy paddock is an ideal location depending on the weather. Mares can also safely foal in a large box stall (12' x 20' or 12' x 16'). It is important to look around the stall and ensure it is safe for the foaling process and your newborn foal. Be careful to remove nails, hooks and potentially unsafe feeders.

Prepare a delivery “go-bag”

Human mothers often have a “go-bag” packed and waiting as their baby signals it’s ready to arrive. You too can prepare a foaling kit with essential supplies. Create a stall-side kit that includes:

  • A clean wash bucket +/- tall kitchen bags to use as liners
  • Iodine or chlorhexidine scrub/ivory soap or baby shampoo
  • Roll of cotton
  • Navel dip (betadine solution or chlordexidine/nolvasan) to disinfect the umbilical area daily
  • Clean towels
  • Latex/nitrile disposable gloves
  • Tail wrap
  • Scissors (consult your veterinarian for use)
  • Notebook and pen to write down key times and changes
  • Naval dip (50/50 2% chlorhexidine +H20) to dip 3 to 4 times a day for the first couple of days based on your veterinarian’s recommendation
  • Thermometer
  • Weight tape
  • Store-bought enema
  • Foal bottle and nipple (lamb or baby), 35 mL oral syringe
  • Black plastic heavy-duty trash bag for saving the placenta +/-baling twine
  • Your veterinarian’s phone number—store it in your phone or keep it in the kit
  • Optional: Colostrum refractometer to measure quality if recommended by your veterinarian

Learn about the three stages of labor

Mares progress through the following three stages of labor (typically within 8 hours).

  • Stage 1: Initial uterine contractions. The mare may lie down and get up, sweat and appear uncomfortable. At the beginning of labor, your mare may display signs similar to colic. This stage is variable in length and can last several hours. There’s no need to intervene.
  • Stage 2: Rupture of the chorioallantoic membranes. This stage starts when the mare’s water breaks, then a white membrane called the amnion becomes visible, ending with the foal being delivered. The foal should be delivered within 15 to 30 minutes of the water breaking.
    • Emergency scenario: If the membrane protruding from the mare’s vulva is red instead of white, carefully cut it with scissors (being careful not to cut the foal) and call your veterinarian immediately. This is a “red bag” delivery, which indicates the placenta has detached too early and is depriving the foal of oxygen.
  • Stage 3: Delivery of the placenta. Within 3 hours post-foaling, your mare should pass the entire placenta. Save the placenta in a bucket or a plastic trash bag to keep it moist. Your veterinarian will want to evaluate it during the physical exam to confirm the entire placenta has passed and check for any abnormalities.
    • Emergency scenario: Call your veterinarian if your mare doesn’t pass the placenta within 3 hours. A retained placenta, even a small tag, can cause infection, septicemia and possibly laminitis.

If all the stages are progressing normally, it’s ideal to leave the mare to foal in peace. Once the foal is delivered and everything looks normal, observe them from outside the stall to allow the mare and foal to bond. There’s no need to rush in and disturb the pair. Also, allow the umbilical cord to break naturally when the mare or foal stand. This is preferred over cutting the umbilical cord.

If you plan to foal at an off-site facility, ship your mare at least a month in advance to give her enough time to settle in and acclimate to the new environment.

Learn more

Your veterinarian has a wealth of knowledge and can help guide you in navigating your mare’s final trimester. A plethora of resources are available for you to learn more. Here’s a sampling of trusted sources:


Do not use Quest® Gel or Quest® Plus Gel in foals less than 6 months of age or in sick, debilitated and underweight horses. Do not use these products in other animal species, as severe adverse reactions, including fatalities in dogs, may result. Consult your veterinarian for assistance in the diagnosis, treatment, and control of parasitism. 

*This product is conditionally licensed by the USDA while additional efficacy and potency data are being developed.


  1. AAEP Expectant Mare: Assuring the Health and Well-Being of the Pregnant Mare.,the%20newborn%20foal%20from%20disease. Accessed January 3, 2023.
  2. Data on file, Study Report No. B951R-US-20-160, Zoetis Services LLC. 
  3. Equine Disease Communication Center. Equine influenza disease factsheet
  4. AAEP Leptospirosis Risk-Based Vaccination Guidelines. Association of Equine Practitioners website. Accessed January 3, 2023.
  5. AAEP Rotaviral Diarrhea Risk-Based Vaccination Guidelines. Association of Equine Practitioners website.,in%20foals'%20rotavirus%20antibody%20titers. Accessed January 3, 2023.
  6. AAEP Botulism Risk-Based Vaccination Guidelines. American Association of Equine Practitioners website. Accessed January 3, 2023.
  7. AAEP Parasite Control Guidelines. American Association of Equine Practitioners website. Accessed January 3, 2023.

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