I'm so sorry your having to deal with this diagnosos. It is so truly hard to see them in pain and ill. My boy Winston passed a couple of years ago developed a tumor on his shoulder blade area within a period of 1 week. It grew tobe the size of a small cantalope. We did the same as you and opted for not surgically removing it because he likely wouldnt have recovered.
Basically we decided to enjoy the remaining time we had with our boy and made sure he was not suffering. The vet prescribed some pain meds and we were able to enjoy about 6 weeks with him before we knew it was time.
He made the decision on his own really, he stopped eating.
It is a very hard thing to decide but it is the kindest thing we could do for our pets.
Enjoy your time and you will know when the time is right.
BTW the tumor we had grew very quickly as well. It was called a mass stromal tumor.
Good Luck! and we would love to see a pic or 2.
Tabitha April 10, 1995 - August 23, 2013
Bomber April 10, 1995 - July 12, 2010
Winston Nov 15, 1999 - September 15, 2011
Sophie Aug 30, 2011
"UNTIL ONE HAS LOVED AN ANIMAL, PART OF THEIR SOUL REMAINS UNAWAKENED"
He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion.