Dog ramp (Univ. City)

Looking for a dog ramp for our 13yr old English Cream. Two weeks ago he got hit with "old dog syndrome," he is healing, but he has a difficult time getting up the three steps to the back patio door. We have to walk him around the house to the front door to come back into the house. We do not think this will improve and would like to get him a ramp. Thank you...