Sort of, and humans sort of can too. The only metabolite of TTX I’m aware of is just the oxidized form. Primarily though it’s excreted “whole” through urine. It actually doesn’t matter if dolphins can metabolize it any better than humans if they’re getting a low dose per kg. Humans eat puffer fish for the same reason, the residual toxin in the flesh gets you a little high. As long as it’s a non-lethal dose, you excrete it (primarily in urine).
It’s also a potent analgesic at low doses, so maybe they do it primarily for the buzz, or to relieve aches and pains.
It’s also a potent analgesic at low doses, so maybe they do it primarily for the buzz, or to relieve aches and pains.