Idon't know what kind of question is this so i just it on health but my dogs always bark at our neighbors dog and they always scratch the the fence and i think also bite the fence i'm concerned about them because it looks like when they bite at the fence they can hurt their mouth

Well, it does look like they bite the fence from the first picture what you need to do is watch them and see if theirs any change the way they eat,drink,and play if you see them not doing any of those things take them to the vet.

Maybe give them things to distract them from the other dogs, or try monitoring them when they are outside, not letting them. cause a splinter in the mouth, throat, or paw is a heath issue and can get infected, also maybe make a schedule with your neighbor, so your dogs can go out a different times, avoiding the other dog fully. good luck though! 

It’s either a or b hope this