I'm just saying' the animal was probably confused as what kind of nutriments he would get from chewing on his leg. Reason why he didn't go all out. Clearly, the dog was pondering the benefit (calories) /vs deficit (how toxic it is) ratio.
Could you imagine if the dog was Cephissus
"Excuse me mister"
"Hello there Dog, how can I help you?"
"I wanted to eat your leg, but do you mind walking around the block a few times, i'm still 17m 31 seconds from my next 483 Calorie meal"