Are the streaks visible „other matter“ or just different coloured stripes in the poo.?
Not everything dogs eat get properly digested, they can’t break down the cellulose in raw vegetable matter for instance which is why it comes out looking exactly the same as when it went in ( veg and fruit need to be cooked or pureed in order for them to absorb the nutrients) so if Kobe‘s eaten dead grass or leaves or whatever, maybe with soil, that could explain the dark colour.
If Kobe‘s otherwise well and active, I‘d just keep and eye out for a couple of days and see if what he‘s eating could explain it but if it continues and you’re in any doubt, take a sample to the vet and ask them to check incase its blood. My dog is raw fed and gets a variety of meats and vegetables, his pooh colour is never the same two days running, it can vary from pale yellow brown to nearly black (beetroot!
) Depending on what you feed, have a look at the ingredients and see if there’s something that might be causing it but if you’re in any doubt, get the vet to check.