A search has been called off for a missing Calgary boater, who is believed to have jumped in the Gulf of Mexico to rescue his dog Toula.

Fraser Horne, a 64-year-old described as an "avid boater," set sail on Friday from his winter home in Florida. His wife reported him missing when he failed to return. The boat was discovered, running in neutral and undamaged, with the man's wallet, keys and shoes still aboard.

After nearly two full days of searching, the coast guard called off search efforts Sunday.

“Suspending a search is the most difficult decision I have to make and our thoughts and prayers go out to Horne’s family and friends,” St. Petersburg Capt. Holly Najarian said in a coast guard statement. "Despite our best efforts, we were unable to reunite Fraser with his family.”

Horne's wife, Michele Horne, told CTV Calgary that investigators are working under the assumption that the couple's 11-year-old golden retriever Toula fell into the water and the man jumped in to rescue her. The dog was found later that night by a passerby on a nearby island.

“There's something she knows and we wish dogs could talk," Horne said. "In rescuing her, there was a strong current that was shifting against him and the boat. From what the data shows, he probably was not able to go back to the boat."

Horne's boat was discovered first near the fishing village of Cortez off the Gulf Coast before the dog was found by a Good Samaritan. Toula was likely in the water for at least two hours, according to Michele Horne. Though she told CTV Calgary the waters are fairly warm in Florida at about 70 to 75 degrees, she said the dog was shivering and exhausted when found and had likely swallowed a lot of salt water. Toula is being given antibiotics and is back to eating, drinking and going for walks.

Horne said she was stunned by the dog's efforts to survive.

"I can't believe that this dog did what she did, swim as hard as she did," she said. "We don't have kids. We love our dogs. They're our kids and he (Fraser) would've done anything for her, so I am so happy she's back with us."

While the official coast guard search was called off, CTV Calgary reported that conservation officers and the county sheriff's office will continue to search daily. The initial search was expansive, said Ashley Johnson, a petty officer with the coast guard.

"We searched over 2000 square miles for more than 46 hours to look for Mr. Horne and unfortunately we were unable to locate him," said Johnson.

According to a statement from the coast guard, search crews from multiple units completed 32 search patterns by air and water in efforts to locate Horne.