I posted to Raven's blog (http://raven.tripawds.com) last night.  But thought that I would cross post this part of it to the forum also.

What happened on Raven's last day Jan. 29: 

He wanted to go for a car ride to town on errands.  He was a bit weak in the hind end and needed a boost into my truck.  But it was like powerlifting 109# of dead weight, quite a struggle.  In town, he was his happy self, barking at dogs in other vehicles, wagging at friends, face in the wind.  When we got home, he couldn't even get up so that I could help him out.  He belly scooted to the edge of the seat and I tried to help, but he pretty much tumbled out on top of me and we both landed in a heap, me breaking his fall.  He happily peed on a bush in the driveway and promptly laid down.  I had to get his harness and support him to hop the house, he laid down just inside the door, never to get up again.  He ate his lunch laying there.  He was never in any pain.  We wagged and flopped excitedly around when my friend came by, his "Auntie Laura" and licked her face.  He did the same for the vet when he arrived.  Tom said it was similar to a Fibrocartilaginous Embolism.  The liver was such a mess (confirmed in the necropsy), that is was falling apart.  He feels a piece actually got swept into the large major artery that passes through the liver and got stuck near the spinal column.  This causes partial or full paralysis in the hindquarters, has a sudden onset, and is completely painless (as opposed to spinal mets).  I believe it happened in the struggle of boosting him into the truck. 

I prayed for months that his end would be quick and he would not suffer.  That was a big request to God, considering that I also refused to put him down as long as he was feeling good.  But God answered my prayer and I am so thankful for that.

Raven's cancer was full of confusing turns.  I wanted answers so my vet Tom took samples post-mortem so that maybe we could get to the bottom of what happened to him.

The lung mets and the liver both came back "metastatic malignant osteosarcoma".  OS???  This was a shock, as he was never diagnosed with OS.  He started limping in April, the xray LOOKED like classic OS, but we biopsied it and it came back benign.  In retrospect, I should have amputated then anyway.  It was diagnosed as a benign bone lesion and to re-xray every 2 months.  The limp never went away, but the lesion never worsened.  Until it did suddenly worsen in the October xray and we amputated then.  The biopsy then came back Chondrosarcoma.  Which was again odd as that is a cartliage cancer and it was in the center of the humerus.

What we believe happened: 

The lesion probably quickly became malignant early on in the summer and metastasized to the liver.  When we discovered the liver disease a month after his amputation, the vets felt it had been there for a long while.  We were doing leg and chest xrays all summer, but never the abdomen.

And we believe that the chondrosarcoma biopsy result was quite possibly "Chondroblastic osteosarcoma" and was mistaken.

The good thing is that this knowledge doesn't change anything or cause me to second guess any of it.  If he indeed had OS from the begining, he did DARN well living with it for 9 months, 6 months before amputation and no chemo.  Even if we'd amputated in April, I couldn't have asked for a whole lot better, he was a 9 year old Rottie after all and had a relatively long life (for them).

I hope that this helps someone doing research and facing decisions.  If you get a Chondrosarcoma diagnosis that didn't originate near cartliage, you may want to ask for input on the likelihood it is still Chondroblastic Osteosarcoma.  Also, I would do xrays of the abdomen also, not just the chest for lung mets.  And if an xray has the classic "thumbprint" or "moth-eaten" appearance in a longbone, I wouldn't have put him through the pain of a biopsy, I'd just take the leg off.  It's already painful, whether malignant or not, and a lesion or cyst is prone to turn malignant later anyway.

Thank you everyone here for all your support through this difficult time.