Updated Jan. 9: Revised to include additional information from Coast Guard.

The search has ended for an Oklahoma pilot who went off-course Wednesday while flying a small aircraft to pick up a rescue dog in Texas, officials said.

Bill Kinsinger (Best Fur Friends Rescue / Facebook)

After 79 hours of searching in the Gulf of Mexico for Bill Kinsinger, a volunteer with Pilots N Paws, the U.S. Coast Guard ended the effort Monday.

Kinsinger was last seen on radar Wednesday when his plane diverted from its original path and headed over the Gulf.

He was flying a Cirrus aircraft from Wiley Post Airport in Oklahoma City to Georgetown, where he was to pick up a disabled husky to bring her to a foster home.

The Coast Guard searched 17,458 nautical square miles looking for any sign of Kinsinger. On Tuesday, authorities said his plane is believed to be thousands of feet below the surface.

"Ending a search is a difficult decision that we put the utmost thought and consideration into," Capt. David Cooper, chief of incident management of the Eighth Coast Guard District said in a written statement Monday. "Dr. Kinsinger was a well-loved man, and our hearts go out to everyone impacted during this tragic time."

Coast Guard crews from Corpus Christi, Florida, North Carolina and Alabama assisted with the search, as did motor vessel that was in the area Wednesday evening, the Mexican Naval Secretariat and the North American Aerospace Defense Command.

The Coast Guard has said Kinsinger may have suffered from hypoxia, a potentially fatal condition where the brain is deprived of oxygen. The FAA requires pilots to use supplemental oxygen if flying above 14,000 feet. Kinsinger had filed a flight plan to fly at 19,000 feet.

On Thursday, several pilots flew from Texas to Oklahoma with the husky to complete Kinsinger's mission.

Kinsinger's son Jacob Kinsinger, 22, said Tuesday that his father "went out a hero".

"My dad was the greatest guy I've ever met and he died doing exactly what he loved, saving dogs and flying his airplane," he said.

Staff writer Tom Steele and The Associated Press contributed to this report.