I can't believe anyone would do this.
And yes, I know exactly what living with a loud mouth dog is about (Ellie) and I would never do that to her.
Someone I know rescued a dog who had this done. Her bark was so raspy and very annoying. I much prefer the regular bark. Your relatives will have fun with the noise when they find out it's worse than the actual bark.
It isn't your responsibility to stop them though and it's not worth a war.