Don't know how much a vet can really tell, all the three vets who looked at the Bagel when I first rescued him could estimate was he was at least 3, probably not more than 5 or so. Now if indeed you have a possible B-day of Oct.31/2006 then even if you ain't sure, go ahead and celebrate, the Bagel kinda thinks October 31 might be his B-day as we always do some special on that day, after all it is a Holiday for us and not because it is All Saints Day or Halloween.