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Vaccinating a Pregnant Mare

April 2, 2012

What’s the best vaccine for a mare nearing her foaling date?


I was going to buy the third Pneumabort K vaccine for my mare and vaccinate her a month before her due date. I was told that I could just get her the regular shots (Fluvac 5) because the rhinopneumonitis vaccine in it would cover the same thing.

My only thought is that if I give this to her now I won’t be giving her the regular vaccines a month before her due date. Is that still OK, and will they still be covered in her colostrum?

For our answer, we turned to Dr. Thomas R. Lenz, veterinarian and senior director of equine technical services for AQHA Corporate Partner Pfizer Animal Health. Dr. Lenz is also an American Association of Equine Practitioners past president and regular columnist in The American Quarter Horse Journal.


It is important to understand that Pneumabort K has a much higher antigen mass than Fluvac 5, and has been demonstrated in efficacy trials to aid in the prevention of abortion due to equine herpesvirus-1.  Fluvac 5 does not have a high antigen mass and is aimed at preventing the respiratory form of EHV, but not abortion due to EHV.  Studies have not been done to demonstrate that Fluvac 5  will prevent abortion, and I doubt very much if it will.

I would recommend that you give the third Pneumabort K dose.  Four to six weeks prior to foaling you should go ahead and give Fluvac 5.  This will protect the mare against eastern and western equine encephalitis, the respiratory form of EHV-1  and -4, equine influenza virus and tetanus, as well as booster her colostrum to provide protection to her foal against those diseases.  You might also want to consider giving her a West Nile Virus vaccine for the same reasons.

— Dr. Thomas R. Lenz
Senior Director of Equine Technical Services for Pfizer Animal Health