dog tumor around anus

Question
My dog was diagnosed yest with a tumor around his anus. I do not know the exact medical term for what it is but from what I understood it is not cancerous. He is scheduled for sugery Monday but I was told it is a high risk surgery because of bleeding. I am wondering what exactly are his chances so I can prepare my children. The vet seemed hopeful it would be a success but he also emphasized the risks involed. Our dog is a mix breed, medium size (70lbs) and otherwise is in excellent health. The tumor appear to be close to the skin and is about 50cent size located directly along the soft tissue of anus.Thank you for any information about this that you can give.

Answer
This is probably a perianal adenoma.  They are very vascular and can bleed, but not enough to bleed out.  Most vets are trained surgeons and they know how do do good hemostasis during surgery. These tumors grow because of testosterone, so if the dog is not neutered, you should also ask the vet to do this at the time of surgery. That often prevents the recurrence of this type of tumor.