I was browsing the issues tracker and found this: https://www2.uthgard.net/tracker/issue/2647/@/Bonedancer_pets_heal_for_incorrect_amount.

Apparently, healer pets in 1.65 healed for 15% of the BD's max health, regardless of which level healer pet you use. Currently, higher level pets heal for more than lower level pets. This means anyone speccing high in BA or Dark has access to not only very fragile healer pets, but very fragile healer pets that are not going to keep you alive in most scenarios. Personally, I upvoted the issue because I very much want to try a split Dark/Supp spec but won't because I like to solo both in PvE and RvR and having access to only lower level healer pets severely gimps my survivability. I would suggest anyone else who cares about this issue go upvote it.