I believe some people use fish antibiotics sometimes since they are readily available and don't require a doctor or vet visit to obtain. I don't know how safe or effective this is though.
My dog gobbled up three 00 caps of Kratom a couple years ago, so probably about 1.5g as I usually filled them around 500mg each. I dropped them on the floor accidentally and he was on top of them lickety split. Tried to get him to open his mouth but he get very defensive and angry. Wouldn't have mattered anyways as he probably had swallowed them immediately.
He was fine fortunately. Just seemed to be extra perky most of the day and then slept a lot that night and through the next day.
I had a roommate who's dog jumped up on the table and ate a good sized bowl of pot brownie mix she was preparing. It was probably a lot of thc, poor dog was practically comatose for over a day with bloodshot eyes. Barely moved from his bed the entire time. Fortunately he made it out the other end mostly ok but he never ate anything from the table again.
I should get a

then be like "ketamine please"
Ive thought about trying to get some tramadol from the vet using my dog. I would only do this, of course, if the dog didn't actually need it. I would never steal from my pet or any friends or family (though I've been close to doing so in withdrawals a few times fortunately I stopped myself). I absolutely love tramadol, haven't had any in like 15 years and wouldn't mind a few occasionally for old times sake.