IMPORTANT NOTE: Dr.Wilson would have serious concerns about vaccinating foals at such a young age if their dams WERE vaccinated or had been previously EXPOSED to WNV. Studies with influenza, EEE, WEE, tetanus, rabies, and EHV have shown that maternal antibody interference extends up to to six months and beyond. Therefore, many foals vaccinated at less than six months of age fail to mount a protective immune response to standard two-dose primary vaccination series.

To avoid this problem, Wilson has recommended that veterinarians delay vaccination of foals from mares which were vaccinated or exposed to WNV until foal is about six months of age. Wilson recommends following series:

FIRST vaccination at six months or older. SECOND vaccination three to four weeks later.

THIRD vaccination six to eight weeks after second dose of vaccine.

What Dr.Wilson and others have found with other vaccines is that many (foals) don't respond optimally after two doses of vaccine even when vaccination is started after maternal antibodies have waned. A third dose gives a little more assurance that ones that haven't responded to two doses will respond to third dose.

Please check with your personal veterinarian for more information on if and when to vaccinate your mares or foals for WNV.