But, then I have become very anxious about the general anesthesia... I called the vet to ask him for the treatment with the local anesthesia, not the general anesthesia. It might not remove the pus entirely and he could have a relapse, the vet said. But... at least the local anesthesia would not kill rabbit and I couldn't risk Mr.Uma's life for his pus.
I'm not sure if my decision was right. Mr.Uma might have to have another treatment in near future if he'll have a relapse and it could be more pitiful. Well... sometimes it's so difficult to have a small animal, the responsibility for its life, but it could be the very meaning of their existence for us pet owners.
After work I went to the veterinary hospital and took Mr.Uma home. After a day spent in the veterinary clinic thankfully he seemed to be lively, ate well and evacuated well. The pus-formed nose might have tormented him and now he might feel better, I hope.
I gave him some liquid medicine (fortunately it has no taste nor scent, I put it on a small piece of apple :D ) and hope his infection would not return.