Hunter pets

I am new to MOP but i have played for years on Wrath and Cata. I just wanted to ask why my hunter pet keeps dying so quickly while leveling. I have changed pets and nothing helps, they die on regular mobs and i am spending all my time trying to heal them. I have never had a pet die before in Wrath or Cata unless i was in an end game raid.
So my question is it all the changes MOP introduced for pets, are they bugged or am i doing something wrong.