HI EVERYONE I HAVE READ IN DOCTORS FOSTERS AND SMITH CATALOG THEY SAY GIVE BOOSTERS EVERY 3 YEARS , DOGS AND CATS ,I HAD A POODLE TINY HE LIVED 20 YEARS I NEVER WORMED HIM OR EVER GAVE HIM A SHOT , HE JUST DIED OF OLD AGE , T TOLD MY VET ABOUT THIS ,HE SAID THEIR IS SO MUCH WORLD TRAVEL NOW THAT THESE DESIES HAVE BEEN BROUGHT TO THE USA. BARBARA MOMBOS MOM