It's harder to get into vet school than med school, you know. And a lot of veterinatry medicines are the same as human medicines. One of my vets noticed, as he was mixing Amoxidrops for me cat, that it was the same stuff that he had been giving his daughter! Plus, a few of my vets have just written prescriptions for my animals that I fill at Walgreens. My cat has his own account there.

As for why dogs get higher doses than humans, it's a two part answer: other animals do metabolise drugs differently than humans. There is a drug that is no longer available, because it causes cardiac problems in humans, but it would help my cat without that risk. The replacement drug would not work for him, though, although it does work for humans. {sigh}

Anyway, the other thing is that there is a crazy sort of thing in medicine about "gotta avoid the potential for addiction..." That means that, in extreme cases, terminal cancer patients still don't get adequate pain relief. Now, there are a lot of reasons for that, including a long standing belief that adequate pain relief through medication will cause dependency and increased pain. That's now being disproved, which should improve things. Now there is much more influence and research being done, most all of which is showing that the best way to avoid chronic pain situations, and complications with things like neuropathy, is to provide strong enough pain relief from the start.

Good luck. I"m sorry you're having trouble like this.