Lazy,
I had almost the same problem with my last lab, fatty tumors, had the largest removed, the last one was cancer, finally went to his lungs, he was full of it. One day he was fine, the next day he could hardly breath, I don't regret putting him down at that point instead of letting him suffer.
Present Lab is allergic to all kinds of things, had Lymes Disease twice, gets horrible ear infections and on top of that is epileptic. We've spent I don't know how much on emergency vet visits for his seizures and he's now on Phenobarb, twice daily, thankfully he's good about taking the pills and I can have my dad take care of him when we travel. We make his food and his allergies and vomiting have disappeared. We keep meds for his ears on hand at all times and antibiotics if he starts to show signs of the Lymes, ... oh and now he's arthritic too.
Did we know all this when we picked up this poor abused dog from the Lab Rescue League, no, would I change a thing, no way! Will he live to be a ripe old age of 14 like most Labs, probably not but at least I know he's had a better life than before he came to live with us.
I spend the money, does it mean it delays my ER, maybe but the companionship and enjoyment are worth it.