A team can use up to 10 designated pitchers but can't have more than two on its active roster at a time.
Abad will, at a minimum, stay with the Dominican Republic for the first round, but could end up staying for the whole tournament.
The situational reliever has a 2.25 ERA in four Grapefruit League outings.
The news of Abad joining the Dominican Republic comes just two days after Hanley Ramirez had to give up his roster spot for the defending World Baseball Classic champions due to right shoulder soreness.
The World Baseball Classic runs from Monday through March 22. In the U.S., games will air live exclusively in English on MLB Network and on an authenticated basis via MLBNetwork.com/watch, while ESPN Deportes and WatchESPN will provide the exclusive Spanish-language coverage. MLB.TV Premium subscribers in the U.S. will have access to watch every tournament game live on any of the streaming service's 400-plus supported devices. The tournament will be distributed internationally across all forms of television, internet, mobile and radio in territories excluding the U.S., Puerto Rico and Japan. Get tickets for games at Marlins Park, Tokyo Dome, Gocheok Sky Dome in Seoul, Estadio Charros de Jalisco in Mexico, Petco Park, as well as the Championship Round at Dodger Stadium, while complete coverage -- including schedules, video, stats and gear -- is available at WorldBaseballClassic.com.