It looks like you are using an ad blocker. That's okay. Who doesn't? But without advertising revenue, we can't keep making this site awesome. Click the link below for instructions on disabling adblock.
Dogs will often eat other's poop because they are lacking in nutrition, cat food is also very high in protein which is like dogs favorite thing! Esecinally the food they eat makes the dog think its delicious. Also for the smell of it, dogs are rooted back to being wild and to blend in with their surroundings they will roll in stinky stuff to not be detected by prey or bigger preditors
Possums eat their own poop because their digestive system sucks a fat one. It can take up to seven trips through its system to digest it fully i.e. possums can eat their poo seven times before having to go find actual food. I don't know about dogs though so this post is pretty irrelevent