A St. Bernard, Guinness, and goldren retriever, Bo, were playing in the yard when a squirrel, darting across the lawn, got their attention.

As is their custom, the two dogs gave chase and were in pursuit. Normally the chase would have ended at the fence but didn't because of snow accumulation.

Returning home from their chase, Guinness found himself in trouble. The thin sheet of ice on the Sidbury River behind their owners' house had given way, and the St. Bernard was submerged in the frigid water.

Bo was determined to see his friend get rescued, however.

"Bo was dedicated. He would not leave his side out there," Valerie Jewell, the dogs' owner, said to a local news station.

Bo barked until someone in the family called the police. The fire department rescued Guinness after he spent 20 minutes in the water. The dog was then rushed to the veterinarian to get warmed up.

Bo was worried when they took his companion away but is better now that Guinness has returned home.