“I think I know a cure for you.” Who is ‘I’ in the story ‘A triumph of Surgery”?

In the chapter "Triumph of Surgery" the cure was cutting off the food and diets.

The care taker i.e. the doctor had not done any treatment but he had given him

plenty of water to drink and less food to consume. so by these, the Dog was

Cured. No treatment or oppression was done.

the mending wall was written by robert frost