A dog that missed its owner escaped its home in the US and walked nearly 20 blocks to visit her in hospital, where she was recovering from cancer surgery.

Sissy, a 10-year old miniature schnauzer, walked straight through the doors at Mercy Medical Centre in Cedar Rapids, Iowa, and right into the hospital lobby, according to a KWWL report.

"She was on a mission," owner Nancy Franck told KWWL.

Nancy's husband, Dale, was letting Sissy and their other dog Barney out to do their doggy business when Sissy escaped early on Saturday morning.

Security cameras in the hospital later caught 10-year-old Sissy roaming the 10th Street entrance of Mercy hospital, prancing around the hospital hallways, looking for Nancy.

"I didn't think they could do it," Nancy told the news organisation. "I thought dogs could find their way home, but this one found the hospital."

Hospital security allowed Sissy up to Nancy's room for a visit.

It was "a big boost -- it helped a lot, just to see her and talk to her," said Nancy.

Before dog and owner were reunited, husband Dale had feared the worst.

"I thought they both came back in the house," he said. " I was panicking. (Sissy's) my baby. I'm sorry."

He looked all over the house and outside trying to find her, and eventually called the animal shelter and Cedar Rapids Police before calling the couple's daughter, Sarah Wood.

"Dad's playing another joke," she thought.

About four hours later, Wood learned it was not a joke.

"Then I get a call from Mercy (Medical Centre) security," said Dale. "They say, 'We have a little dog here.'"

Sure enough, it was Sissy.

Wood went to the hospital security office to pick up Sissy, and says she was waiting in the office looking out the window when Sissy turned around and gave Wood a clear look.

"'About time you showed up, I've been here for a while now,'" Wood said, mimicking Sissy. "'Let's go see Mom, then you can take me home.'"

The Francks say Sissy has never run away from home, and could not have had any idea that Nancy was at Mercy -- or even where Mercy was.

Nancy is hoping to be released from Mercy soon.