HAMILTON - Susan Gribbell would never let a dog drown.

As soon as she heard a loud "crack" and saw the two West Highland terriers fall through the ice at the half-frozen pond in Patton Park, Gribbell dove in to rescue them. In her winter coat, hat and boots, she swam about 25 feet across the pond, then hit ice. She broke through it until she reached the dogs and scooped them out.

Then the cold hit.

She felt pressure on her lungs and found it hard to breathe. When she tried to get out, the ice around her - only about a half-inch thick - fell apart. The water was about 8 feet deep.

"I never really thought I was going to die," she said. But she was cold and tired, and when she looked up, she was relieved to see a police officer on the shore.

Patrolman Brian Shaw was driving by Patton Park around 9 yesterday morning as part of his normal patrol.

"I guess naturally I always look at the park," he said. This time he noticed four dogs running around. They were the two terriers, which Gribbell was dog-sitting, and her own two yellow Labrador retrievers.

"They weren't acting normal to me," Shaw said. He stopped and thought he saw a dog trapped in the pond.

"As I got closer, I could hear the woman. She was screaming, 'Help,'" he said.

Shaw called for backup. Then he grabbed a flotation device from his cruiser.

"When I threw the rope, she had no energy," he said - a sign hypothermia was setting in.

"I couldn't hold onto it," Gribbell said. "It was slipping through my fingers, and it was hurting."

By then, more police officers and Hamilton firefighters had arrived, and they helped Shaw slip into a cold-water rescue suit. Gribbell floated on her back to conserve energy as he jumped in and then grabbed her and the flotation device. The officers pulled them both to safety.

She was taken by ambulance to Beverly Hospital, where she was wrapped in blankets. It took about a half-hour before she stopped shivering. Two hours later, she was back home.

Gribbell said the two West Highland terriers were chasing swans when they fell through the ice. Neither belonged to her - one was her sister's dog, and the other she was dog-sitting for a friend - and as the adrenaline pumped through her body, her first thought was to save them.

"I chose to swim stupidly through the water," she said.

Gribbell had been in the water for at least 10 minutes - probably closer to 15 or 20 - by the time Shaw got her out, he said. The water was about 36 degrees Fahrenheit, and some of the surface had frozen over the night before when the air temperature dipped into the 20s.

Police say there's no question Gribbell could have died if she'd stayed in the water much longer.

"Thank God the police were there," Gribbell said.