Pregnant Mare Management


 First ultrasound for pregnancy:  14-16 days post ovulation

This is the earliest time at which the growing embryo can be identified ultrasonographically, and if twins are present, in many cases both embryos can be visualized and the condition dealt with at this time.  However, in some instances a smaller embryo (usually due to the mare ovulating a second follicle days after the first) can be missed in this exam.

Recheck pregnancy with ultrasound:  25-40 days post ovulation

Early embryonic loss is not uncommon in mares (approximately 10% of pregnancies in mares).  This ultrasound allows us to confirm that the pregnancy has progressed and a heartbeat can be detected, and to reconfirm that a twin pregnancy has not occurred.  If the mare has lost her pregnancy, a check at this time can usually identify this in time to rebreed the mare that season.



5 Months gestation:     

Fall pregnancy examination

First Rhino vaccination

Rhinopneumonitis (caused by Equine Herpesvirus Type-1) is a respiratory disease of horses that can also result in abortions in mares.  A series of three vaccinations with high antigen vaccines designed for pregnant mares is recommended to reduce this abortion risk.

 7 Months gestation:     

Second Rhino vaccination

 9 Months gestation:     

Third Rhino vaccination



3-4 weeks prior to expected due date:

General physical exam

Assess the mare’s general health and condition, and identify any potential complications as she approaches foaling

Reconfirm pregnancy

Booster vaccinations

3-way (EEE/WEE/Tetanus),  West Nile,  +/- Flu/Rhino (dependent on risk level)

Open Caslicks (if present)

 2-4 weeks prior to expected due date: 


This can be done by the veterinarian when the final vaccinations are given, or if given by the owner would ideally be done 2 weeks before foaling


For more information about nutrition and other care during your mare’s pregnancy, please refer to the AAEP “Expectant Mare” pamphlet provided and/or contact us at Burwash Equine Services.

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