If your dog was diagnosed with hemangiosarcoma and his paws are cold I'd be very concerned that his blood is not circulating properly or that he is bleeding internally.
What color are his gums? Tongue?
How is his energy level?
Is he eating and drinking?
He was just diagnosed with a tumor on Friday (yesterday). They don't know if it is hemangiosarcoma but the vet suspects that it is. We know that his blood is not circulating properly with any exertion- he will sit down or lie down on the pavement and not get up- but he has not had cold paws before.
His gums are light pink. His tongue is a bit pale but light pink. He is eating the foods he likes the best- ham from Whole Foods - and is drinking a lot of water. More than usual.
I'm sorry to hear that he was diagnosed with hemangiosarcoma.
I recommend keeping him as comfortable as possible and keeping the exercise to a minimum. His paws are most likely cold due to poor circulation.
If his gums turn white and he seems to be having trouble breathing it would be a good time to bring him in.
I was in a similar situation with my last Golden Retriever and I know how hard this can be.
Let me know if I can do anything else to help.