Yes, after reading up on it over the last couple of hours, just for fun, I found out something similar. The elephant was apparently already scheduled for "execution", and the method of using electrocution to kill it was only decided after they received backlash for planning to hang it (somehow?). The event was, however, filmed by the Edison company, and the film was credited to Edison himself - which is still a pretty messed up thing to do! Either way, the Topsy song from Bob's Burgers is incredibly catchy :)

The part about pets is still factual, though; he actively backed and supported a campaign which paid kids a quarter for pets - be it their own or ones they'd stolen from their neighbourhoods - and then used them as a demonstration to 'prove' the dangers of AC power. In fact, they would first use DC power to torture the animals, only to then switch to AC power to kill them. Still barely scratches the surface of the messed up stuff he did, of course.