Edison electrocuted animals using A.C. current to discredit Tesla.
Edison was a shameless mechanic who browbeat his help and stumbled his way to great success and wealth and that is a polite paraphrase of what Tesla thought of his former employer.
I remember that Tesla did not like Edison at all after working for him.
Perhaps that was why. ( The animal torture thing)
Edison did this in order to prove A.C. was more dangerous than D.C.. True as far as it goes but Tesla proved that A.C. would work for transmisson purposes better than D.C. and Tesla was correct.
The electrocution thing backfired -- Edison was trying to win the war of the currents, and in order to do that was trying to show that AC power was inherently unsafe. Instead, the electrocution by DC was found to be much more effective, and that's what's used today.