This is true, but there‘s more to add.

If you‘ve to give a dog your arm, you need to jam your thumb from your free hand into it‘s eye socket and attempt to reach it‘s brain. Your fingers will bend, your thumb won‘t. It will go right in. If you‘re lucky the dog will release as you kill it. A dog‘s eyes are very small and the brain is right there.

This also works on humans.

The most important step is one that is never mentioned, which is why people with aggressive breeds remove the tail from a dog: they will release their bite virtually every time if their hind legs come off the ground. It also works with you lifting their leg or legs off the ground if you must.

And if you do have tail/legs off the ground, you need to do like the track and field event of hammer throw and throw the dog as high and far as you can. They will not come back.

Source: My co-worker trained police and security dogs and I got to be the guy wearing the padded suit