Final answer:
Steinbeck's dog was likely treated at a small dog hospital near where a walk began for the story's characters. The facility tended to dogs with various ailments, releasing them after recovery, as seen with a once ill Irish setter.
Step-by-step explanation:
Steinbeck's dog, referenced from a passage, likely received treatment at a little dog hospital. The context implies that this hospital was located near where the characters of a story started their walk, possibly in the same city as the protagonist's acquaintance, Marcus, who let out the convalescents.
It can be deduced that the hospital provided care for dogs that were ill or in need of medical attention, as evident from the fact that a dog thought to have distemper was acquired from it by Marcus.
The mention of a finely-bred Irish setter, once believed to have the distemper but actually suffering from a little catarrh, highlights the kind of care and attention a dog could receive at such a facility. This treatment allowed the dog to eventually be considered a 'winner' by Marcus, who recognized its value and potential despite its initial health scare.