>>39776
>eat a very specific type of grass
Yeah, they picky with that.
Not all the dogs vomit it out. And those who vomit frequently just eat it back so the grass ends in their intestines anyway. And then it comes out on the other end fairly the same as it went in except with more poo on it. Yeah, they eat it to come over some discomfort in their belly or more toward the rear. Or just because they want to eat more and they know instinctively it does no harm to them. Wolves eat as much as they can on every occasion because it's not sure when they will be able to eat next. It's an ancient instinct in many dogs to eat as much as possible, full belly is always comforting to them.
They also capable of eating quite a few types of plant based edibles from fruits to roots and depending on how simple or complex the carbohydrates they eat some of that they even can digest. Some stuff are fine, but some causes gas, others are simply poisonous (and then depends how much they eat).