So if I have an animal companion with the Trip ability (say the leopard) does it provoke an Attack of Opportunity? The Feat Improved Trip is not available to Animals so I thought maybe they did not need it.
Many thanks.
Not for the trip ability with the attack. To trip normally, they do.
http://www.d20pfsrd.com/bestiary/rules-for-monsters/universal-monster-rules #TOC-Trip-Ex-
"A creature with the trip special attack can attempt to trip its opponent as a free action without provoking an attack of opportunity if it hits with the specified attack. If the attempt fails, the creature is not tripped in return."
Right on. What a nice little ability.