The Dutch women won relay silver at the world championships in Kazan, Russia, last year with triple Olympic gold medallist Ranomi Kromowidjojo, Femke Heemskerk, Maud van der Meer and Marrit Steenbergen.
More than four swimmers are often included in relay teams, with reserves slotted in for the heats before the top four compete in the final.
Dekker was also down for the 50m freestyle and 100m butterfly.
The seven men in the squad, who will train in Sardinia before flying to Brazil, will be led by European 200m freestyle champion Sebastiaan Verschuren. Ten of the 17 are Olympic debutants.
"It's good to see the mix of experienced Olympic swimmers and young talents," said Dutch swimming managing director Jan Kossen. "The number of novices at these Games also gives confidence to the more distant future."
(Reporting by Alan Baldwin, editing by Toby Davis)
