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VACCINE RECOMMENDATIONS
We should try to maximize the impact of our vaccines based on timing, frequency and choice of individual vaccines.
Heather Smith Thomas resides on a ranch near Salmon, Idaho. As a freelance writer for many years, her equine health and manage- ment articles are a regular feature in Speedhorse Magazine.
for Mares and Foals
by Heather Smith Thomas
There are certain vaccinations that are currently recommended for all horses. Others are optional, depending on location and circumstances. Guidelines for vaccination of mares and foals change periodically, as new vaccines and new knowledge come along. Veterinarians recommend following the vaccination guidelines provided by the American Association of Equine Practitioners (AAEP). These can be found on their website. These guidelines are
a good place to start when developing a vaccination program/schedule. The best protection of foals begins with vaccinating the broodmare at strategic times during her pregnancy. This results in passive transfer of antibodies to the foal through her colostrum if the foal ingests an adequate amount of her colostrum shortly after birth.
BROODMARES
Dr. Caitlin Rothacker, of New Bolton Center
in Pennsylvania, says it’s always a good idea to have broodmares well-vaccinated prior to breeding. “The basic vaccines we recommend for all of them are tetanus, EEE, WEE (often combined in the same vaccine product), West Nile Virus and rabies. These are the so-called core vaccines, and then there are some optional additional vaccines that can be given based on where you live and what the risk factors are,” she says.
“Influenza is considered a risk-based vaccine. For well-vaccinated mares, we booster them with the inactivated vaccine 4-6 weeks before the expected foaling date. For unvaccinated mares, we tend to use the inactivated vaccine in a 3-dose series, with the last dose given 4-6 weeks before foaling. Influenza tends to be a disease that occurs where there is a high density of horses with frequent introduction of new animals.”
Strangles is also a risk-based vaccine. “The decision on whether to vaccinate or not should
be discussed with your veterinarian. Broodmares typically receive a booster with the killed vaccine 4-6 weeks before foaling if they have a strong vaccination history. If not, a 2 to 3 dose series can be utilized according to label directions,” says Rothacker.
“In this part of the country, we vaccinate for botulism, and some places near open water might have increased risk for Potomac Horse Fever,” she says. Find out which vaccines are recommended in your specific region. Your local veterinarian can advise you on this.
If the mare is vaccinated prior to breeding, she can then be boostered 4 to 6 weeks before foaling
with tetanus, WEE, EEE, West Nile and rabies,
so she has strong immunity to pass along to the
foal via the antibodies in colostrum. “While the different West Nile vaccines are currently unlabeled for broodmares, many veterinarians feel the risk of vaccine complications is minimal compared to risk of contracting the disease.”
“During pregnancy we also recommend that the mares be vaccinated against herpes virus because it
can cause abortion. We do that at 5, 7 and 9 months’ gestation to ensure adequate immunity,” says Rothacker.
FOALS
If the foal is from a mare who has been well- vaccinated, we have one set of guidelines. But if
the foal is from a mare with a spotty vaccination history or had a bumpy start in life without enough colostrum, there is another set of guidelines,” she says.
The foals from well-vaccinated mares should receive tetanus, EEE, WEE, and West Nile in a 3-dose series, starting at 4 to 6 months. The maternal antibodies from colostrum should protect the foal during its first 4 to 6 months of life, so we vaccinate these foals during the transitional time when that protection is starting to wane.
“In the southern U.S. where the vector season is longer, we recommend starting these vaccinations earlier in foals since they will be at risk sooner from the mosquito-borne diseases. You can start at 3 months of age in this situation,” she says.
“Rabies is a 2-dose series, and we start that at 6 months of age so as to not have maternal antibody interference. If the dam was unvaccinated for rabies, we can begin the series at 3 to 4 months. In this situation (an unvaccinated mare), foals should also be started on their other core vaccines earlier. You can start tetanus in the 1 to 4 month range. The EEE, WEE, and West Nile can start at 3 to 4 months.”
If the foal has no maternal antibody protection against tetanus, antitoxin can be given soon after birth if the foal had possible exposure, such as a wound. The vaccine for tetanus (toxoid) is effective fairly young, but your veterinarian could make the decision whether to administer toxoid or antitoxin if the young foal is at risk.
A few years back there was some controversy over when to give foals their first influenza vaccinations. “We usually don’t start before 6 months of age,
and we recommend use of the inactivated vaccine,” says Rothacker. The modified live virus vaccine,
30 SPEEDHORSE, March 8, 2013
EQUINE HEALTH