Joules you mention the boxer you look after did lots of poos when fed on hills, i've never had a dog from a puppy before and therefore dont know what contitutes 'loads' of poos but i do find she does go quite often say around 5 or 6 a day? She has been fed on hills from when we got her home so i dont understand why she would all of a sudden start eating her poo, one thing i am worried about is that it may have something do to with her being left alone and having to poo in her pen when she's used to going outside, or eating it out of boredom or frustration. When we do leave her she always has lots to chew on and play with but the fact that she attempted to eat the one she did in the garden tonight has maybe put my mind slightly at rest on that matter.
Re the boxer - he is an adult and does at least 4 hooooge poos a day
Coco is nearly three and usually does 2 small ones a day (she is fed on BARF so not much waste in her diet) when she was on Naturediet/Arden Grange she did 2 larger ones. Obviously a small pup does more poos but I swear with the boxer more comes out than goes in!
I have various other doggies to stay on various different diets and his is the only one Coco likes to eat - he is the only one I have had that is fed on Hills
It may not be the food but seems to make sense to me. I have heard this about Burns food which is an excellent food with no nasties in it so can't explain that one
Don't worry about poo eating in a pup - it seems to just be something that a lot of them do, not down to boredom or anything you are doing wrong.
Just persevere with distracting, cleaning it up as fast as you can etc and hopefully she will grow out of it