[vacri]

The author is wrong in saying that the testes are not protected, though. They're quite well-protected, with a leg on each side. Simple proof of this is that it's clear when these are damaged due to the pain, but most men will only experience this pain a couple of times in their life.

The testes are even more protected in quadrupeds, far away from any frontal fighting or sparring. And if you're a quadruped that is being chased by something that can damage your testes from behind, you have far bigger problems than damage to your testes.