The El Paso Fire Department said the dog, named Cosmo, was with his owner who began suffering a medical emergency on Wednesday.
When he realized his owner was in distress, the pup immediately ran in search of help.
Rescuers said a good Samaritan saw Cosmo and when they tried to get closer, the dog led them to his owner. The good Samaritan then called 911 and the dog's owner was rushed to the hospital for life-saving treatment.
"Who's the goodest boy of them all?" first responders wrote.