Both the war animals and war beasts are noted as only having the sentry special rule. This results in them not having any sort of (natural) weapon to attack with, and thus hitting last in any combat. The same goes for warmounts with their trample attacks.
Is this intentional? I'd expect war animals/beasts to at least have something like Bite 0 to be able to pose somewhat more of a threat, since otherwise it's rather easy to first just focus them to reduce the squad's attacks.