Patricia Drauch of Marcellus Township said she was doing yard work Sunday when her son, Stanley, plunged into the pool, ABC News reported Tuesday.
"Stanley usually follows us around and I went into the garage to put away some stuff and came back out," Drauch told WBND-TV, South Bend, Ind. "Just in a moment he wasn't behind me."
Drauch said her family dog, Bear, was on the scene and jumped into action when he saw the toddler in distress.
"Bear put his back underneath Stanley's back to keep him from going under any farther," she said. "I don't know where I'd be if Bear didn't go in for him and keep him up out of the water before I could get to him."
Drauch said Stanley wasn't breathing when she pulled him from the pool and she drove him to the Marcellus Fire Department when she couldn't get cell reception to call 911.
Drauch said the boy was taken to the hospital and released later in the day. She said doctors determined he had not suffered any ill effects from the incident.
The mother said she credits Bear with saving Stanley's life.
"He's my hero," Drauch said.