Ellie May, I dont tie him outside cause then the cat plays with him and he always gets tangled

The cat is so evil running around and sometimes he gets loose (He pulls his collar off !).
I have a baby gate but I cant put the babygate where the main door is , I can only put it in the other door that leads to the garden.
My aunts dog only went over the line once and got a shock, since then she always was just in the garden, she knew right away that she couldnt go out of the garden, Fido would propably just go few times out of the garden and then learn.
Ofcourse I would ALWAYS be outside with him, I would never leave him in the garden without supervision, I would be there with him allways when he's outside, also he does not like being outside alone he would bark then constantly, so I have to be outside with him
Fido is no small yorkie he is somewhere between 14-15 pounds
My aunt uses this electric fence for 3 dogs, all very healthy =)
Im moving soon, we havent found an apartment yet but I hope we find some apartment or house with fenced yard

that would be the best...
Im just wondering about this electric fence for the future, I will most likely move to my aunt in the US in few years and take Fido with me, she has electric fencing and then I would propably buy a collar for him so he could also run loose in the yard but I would ALWAYS be there outside with him.
How can this affect the health of the dog? what can happen if I would use this kinda collar?
I would OFCOURSE use the collar first on myself

!