I live in NJ and
in an area with heavy mosquito population so we vaccinated last year &
boosted this year. 2 Arab & 2 QH geldings ages 17 - 22. We split
spring vaccinations by 2 weeks and none had any adverse
effects.
The possibility
exists that they had antibodies but also maybe not. This is Lyme disease
area also and many horses have had tick bites over the years and some probably
have antibodies but we still get a number of cases of horses with Lyme every
year. My point is that unless you test for antibodies you don't
know and you don't know if the levels are high enough to prevent disease so
vaccination is probably safer than taking your chances with
disease.
It's that
whole risk/benefit ratio as with smallpox
vaccine.
