Oh I am so shocked by this and so very sorry. Your poor sweet boy...
Hemangiosarcoma is the absolute worst-case scenario. I know. My own dog passed from tis. You would not guess anything was wrong with her, though she had sprouted 3 subcutaneous lumps.
The vets find this very hard to diagnose in the early stages. This cancer is known as 'the silent killer' because the dogs don't show signs of illness. An incisional biopsy is controversial. Yes it removes the one tumour, but it doesn't solve anything. The cancer is in the blood vessels and is already spread through the blood system by the time it is discovered.
Personally I challenge your vet doing an incisional biopsy. A bit of foresight would have helped. An ultrasound scan first of the mass would have been better, after a needle biopsy. The needle biopsy coul have given the vet some clues about that particular tumour, although on Lab. results it would probably have come back as 'inconclusive' result (as only blood would have been aspirated) But with experience a vet should be able to tell if a needle aspiration behaves in a certain way with a small amount of blood in the needle, an ultrasound should be run. This should show if the tumour is 99.999% likely to be Hemangiosarcoma.
There is no cure. They ought to make that clear. By the time it is discovered the best that can be offered without stress to the dog and invasive procedures (in my opinion) is hospice care. Chemo doesn't cure it and can give (sometimes only) a few more weeks and that's all.
It is a very cruel cancer. I wish there was some early diagnosis or regular screening could be done for this.
My heart goes out to you in your grief.
Okay, so just figured i'd give an update to this thread... Just in case anyone else has a problem like what we encountered....
It took until about the 15th of January for our vet to get back in town, by this time that mass had doubled in size, we rushed him in the day they re opened their doors, booked him in for surgery... they ended up cutting the mass out, suturing him shut and we sent the now tennis ball sized lump in for a biopsy. (Remember here, this went from being the size of a damn 25c piece to a tennis ball from Dec 25 - Jan 15..) 2 days after we got him home, he was all swollen an engulfed again the only thing missing was the lump - back to the vet we go. Turns out that he had cancer. A Hemangiosarcoma .. a type which targets the blood vessels, causes a rather nasty tuma, and when the vet tried cutting it out, the blasted thing was all wrapped up around his shaft and they could only cut part of it out, the rest of it was still bleeding... constantly. The vet popped the last 3 stitches, and left him to "bleed it out.." didn't put a cone on his head, a drainage pipe, or anything... he was hemoraging blood out of his back legs on a regular basis, and they said it was "fine for him to lick himself clean.." i'm still unsure about this ****.. But, 1,500$ later... and the poor dog on antibiotics and sedatives... we decided to put him down. He didn't act like he was in any pain at all during the entire month we had him home, he was still running around, bolting up and down the stairs, didn't even bat an eye like it hurt.. was still pulling me and my husband around on his leash to the point the vet said he was the strongest dog he had seen in his 40 years of practice... The day we decided to put him down.. (Feb 9th, the day after my sons birthday.. we threw a big bash for him and the dog together, lots of photos, gave them a chance to say goodbye ect..)The vet told me that they had some "new" sort of thing they could offer... a treatment which would run us 1,000$ a month, and there was a chance that it could put any other tumours whi ch may surface into remission.. but it wasn't a cure, it's only a possibility, and it might not work at all.. After not more then 3 days before hand telling us he had no chance in hell, and that he had another month left in him at the most IF we where lucky and his will to survive was strong enough to reproduce the blood he was losing ... (dripping out all over my house, and having to keep him sedated to the point his heart beat slowed down to slow the bleeding down..) - Personally, I'll never take another damn animal to the vet we seen if I can help it. I think he seen our boy as a cash cow.. and knew from how strong he was and how much he was fighting this that he would have survived another month and was just wanting the extra cash he could get knowing my husband just got his taxs in..
I can't say what this is. I really don't know. But I don't think it can wait until 15th January to be seen by a vet, especially as it has grown quite quickly. I can't make guesses about it.
I know you're in a countryside area and no other vets in your town. But is there a town anywhere you could get to, with another vet who could take a look at this? Or anyone who could take you and him there in a car?