International Dairy Queen Inc. will be getting a new chief as the company continues an effort to modernize its  77-year-old brand.

The Edina-based company said Thursday that President and CEO John Gainor will retire at the end of the year and current Chief Operating Officer Troy Bader will take his place, effective Jan 1.

The company declined to make the executives available for interviews. An announcement about the change indicated the move was planned and was part of an “active process of talent development and succession planning.”

Dairy Queen, a subsidiary of Berkshire Hathaway Inc., has been replacing its old-style restaurants in recent years to compete in the cutthroat quick-service restaurant category. Through its DQ Grill and Chill remodels, the company has updated its seating, beefed up its menu with more food items and tried to offer more specials and creative ice cream treats. It also has made a deliberate push to expand internationally.

Bader, who was hand-picked by Gainor, joined Dairy Queen in 2001 and has been in his current role since 2011. He manages the company’s marketing, operations, franchise development and the supply chain in the United States and Canada.

Gainor has led the company since 2008 and has overseen what the company described as “record reinvestment,” which included rapid expansion of the Grill and Chill concept.

Dairy Queen now has more than 6,700 locations in 25 countries, including 4,300 in the U.S. Just two restaurants, one in Richfield and one on Normandale Boulevard in Edina, are directly owned by the company. The rest are run by franchisees.

Late last year, the company announced it would extend its international reach into South Korea, aiming to open 50 locations there in five years. Under Gainor, much of the company’s global growth was concentrated in nations known for hot weather, such as Kuwait, Saudi Arabia, Taiwan and Vietnam.

DQ often would tweak menus to appeal to local tastes, offering ice cream flavors such as green tea with red bean. In the Middle East, the chain rolled out beef kofta, a spicier, gyro-type sandwich.

“John has done everything I hoped for — and more — in accelerating IDQ’s growth in the U.S. and internationally,” Berkshire Hathaway CEO Warren Buffett said in a statement. “I thank him for both that and for the development of an outstanding successor, Troy Bader.”