Answer :
I am thinking it is his need to comfort his friend....I was first going to say his concern for his sled dogs...but his statement " they do get on the nerves horrible " , without seeing the rest of context, might be talking about the sled dogs getting on his nerves.
The answer is “His need to comfort his friend” definitely. I know this because Henry said, “They do get on the nerves horrible,” he sympathized!