Is my dog suffering from senior dog problems or cancer?

If he's been diagnosed with lung cancer, this is probably as bad a diagnosis as it gets because once on the lungs, it will go right round his system and because of the metabolism of the dog (fast), he won't have long. Right now, I'm really sorry to say, your old boy is in trouble (running could indicate he's trying to run away from the pain he's in) and rather than allow lingering, which we have never done however sad it is, we've always put our own emotions to one side, and helped ours over the final hurdle.

With the advice of your vet, who will give you something for him if there is anything to be done, believe me, make your decision, whatever that might be.

Just to add, look into his eyes. So often when there is a good connection between pet and owner, you'll see it - he'll let you know life has become too much of a burden. Please help him.

I found that some dogs when they get ready to die want to get away from where they are at and hide. But if that's not it maybe it is the cancer it may have worked its way to its brain or could also be its nerves he may feel traped and can't breath at times.. But GET YOU A GOOD VET FOR SURE!

He is in distrees because of the cancer and I would go ahead and put him down. No sense in letting him go through this.

do what is right for your dog ..................... he has had a great life with you