Final answer:
Adam took Henrietta to the vet in the Macy's bag, after which he and Marcus had a beer.
Step-by-step explanation:
Adam was headed to the vet with Henrietta in the Macy's bag. From the excerpt provided, we learn that after Marcus and McTeague retrieved the dog, they took it to the hospital, which in the context of pets refers to the veterinarian's office. The men then left the dog whimpering behind the wire netting, which is a common feature in veterinary clinics to separate and house animals. After this visit, they proceeded to have a drink, indicating the completion of their task.