i have a few random and unscientific thoughts about this (if anyone can cite a study on the safety or efficacy of using electric dog collars on humans, i'd be interested in reading it... would be fun to know which peer reviewed journal it is published in). Meanwhile, we have anecdotal information and the 'authority' that goes with it.
Here's some technical info on dog shock collars:
"Comparing the effects of shock collars with other electrical stimulation products, Dr. Dieter Klein has stated that, "Modern devices ... are in a range in which normally no organic damage is being inflicted. The electric properties and performances of the modern low current remote stimulation devices ... are comparable to the electric stimulation devices used in human medicine. Organic damage, as a direct impact of the applied current, can be excluded.” Shock of this nature carries little energy (on the order of millijoules, 1 millijoule = 0.001 joule ). "At 0.914 joules the electric muscle stimulation and contractions a human receives from an 'abdominal energizer' fitness product is exponentially stronger — more than 1,724 times stronger— than the impulse a dog receives from a pet containment collar set at its highest level.".
A "remote trainer" set on a low level emits 0.000005 joules (5 microjoules).
A "bark collar" set on a high level emits 0.0003 joules (300 microjoules).
A "muscle stimulation machine" set on a "normal level" emits 2.0 joules.
Set on a "high level" it emits 6.0 joules.
An electric fence energizer [a "charged fence" – not a pet containment system] emits 3.2 joules.
A modern defibrillator can emit up to 360 joules."
https://www.petrainer.com.au/pages/shock-collar-information
Here's some technical info on human defibrillation and pacing. In hospital, we typically use a setting of 140 joules the first time we shock someone in a disrythmia. The stuff seen on tv and in movies where they shock someone who has arhythmia (i.e., the straight line seen on the heart monitor represents no electrical activity, no heartbeat), is the opposite of what is really done. We (healthcare workers) don't shock someone who has no heartbeat. The shock we deliver is to stop the heart, not start it. If it is in a life threatening disrythmia, we shock the heart to stop it, and it restarts on it's own... sort of like rebooting a computer and hoping it will self correct. If a person has a straight line, no heartbeat, we do CPR, which is mechanical manipulation of the heart to circulate the blood.
https://www.aclsmedicaltraining.com/adult-cardiac-arrest-vtach-and-vfib/