Why is he tempted to keep Tricki on as a permanent guest?
The narrator is tempted to keep Tricki as a permanent guest because of the luxurious items Mrs Pumphrey sends for the dog's recovery. To build his strength and enrich his blood, she continuously delivers fresh eggs, wine, and brandy.
Since Tricki does not consume these items, the narrator and his partners enjoy them instead. They eat extra eggs for breakfast, drink wine during ceremonial lunches, and reverently drink the brandy by the fire. These delicacies make their days deeply content, creating a strong temptation to keep Tricki on permanently just to continue receiving these treats.
Explanation
The question asks for the reason behind the narrator's temptation to keep Tricki permanently. In the chapter 'The Triumph of Surgery', Mrs Pumphrey sends various expensive items like fresh eggs, wine, and brandy for Tricki's recovery. However, Tricki is on a strict diet and does not consume them. Instead, Dr. Herriot and his partners consume these luxuries, making their days 'of deep content'. This selfish but humorous enjoyment of free, high-quality food and drink is the exact reason he is tempted to keep the dog as a permanent guest.