No. A sweepstakes is for any dog eligible to compete on
the day of the show. There's no prior nomination required. A
sweepstakes covers a time period counting from the show
date. A Futurity covers the same time period each year even
if the date of competition changes.
If a puppy is too old on the day of the Sweepstakes to
compete in the class, it cannot be entered. But in a
Futurity, the puppy may be more than 18 months old on
Futurity day and still be able to compete if it was born
during the Futurity year.