You might want to edit your question, from ‘drain’ to train a dog. The answer is yes and no. yes, it can be harmful if the shock collar is used harshly in a cruel and thoughtless manner. I know of a family whose children were allowed to use the remote to shock their little jack Russel terrier for being too hyper in the house. This of course made things worse. The puppy became aggressive. I would have liked to put that collar on the parents, to correct them for bad parenting!
Some trainers use shock collars for training hunting dogs, who have to work at a distance. In skilled hands, electronic training systems can be a great tool, but in the wrong hands, a torture device. Shock collar systems can be incredibly useful for teaching a puppy to stay within the boundaries of a property.
That’s what I use mine for. I have a stubborn Pyrenees X who sometimes strays off our ranch. He’s not a problem when the weather is bad, but on a beautiful fall or spring day, he forgets that he is required to stay home when given free time on the yard. A shock correction at the right time, is a very quick and thorough way to teach him that bad things happen when he leaves the yard without my permission.
I use a high correction for those times. A light static shock does not give him enough correction. When I hear him yelp, from a far distance, I know he has just learned that stepping off the yard is bad. It will save his life. We live too close to neighbours and a busy gravel roadway with a lot of farm traffic.
For that reason too, my dogs are NEVER taken off the yard, except by means of a vehicle (to the Vet or Groomer).
I once taught a dog aggressive little Pom that biting another dogs’ face, for saying hello was a definite No No. This little dog did this consistantly, luring another dog to come on over with an invitation to meet and greet… and then Chomp! I caught her in the act twice, and used a high correction. She never did it again.
It’s important that the dog associate un acceptable behaviour with the correction, not with you and the remote. That’s where a knowledable trainer comes into the picture.