He will be due the flu as long as you havn't gone over the due date otherwise you will have to start them all over again, the tet lasts for 2 years i think. But to be sure just wait to see what others say.
Kate x
At a guess, would think that horses are much more likely to come into contact with tetanus as it lives in the soil, and they're more likely to cut themselves. But that is a guess! And vets do say that the immunity lasts longer than a year (sorry, don't know how long) but competition rules err on the side of caution.
of course the vaccines dont run out on the day, but for competition purposes there has to be a cut off point somewhere and if you start allowing one day over, then why not 2days etc etc - you have to draw the line somewhere.
and horses are more prone to tetanus than us. they are so prone to getting tiny cuts which then almost instantly come into contact with the soil. we are less likely to cut ourselves and then go rolling around in the dirt. if you do actually have a contaminated wound and go to the docs they will ask when your last tetanus jab was and give an anti-toxin as well if it's more than a few yrs just to be on the safe side.