The case of the colour changing dog poo

Do you remember the white dog poo which was prevalent when you were a child (depending on your age of course)? Cast your mind back to those rocky, calcified remains that your parents told you not to touch when you were an inquisitive child. Where did they all go?

No, it's not because dog owners have increasingly realised the importance of civic duty. The reason is that the formula in popular dog foods nowadays have changed to have less bone meal and therefore less indigestible ash/calcium. Granted, I've had a look for some more concrete sources to this assertion, but have only really found anecdotal evidence.^[1][2][3] Some people have also speculated to the prevalence of bovine spongiform encephalopathy (Mad Cow Disease) to the decline of bone meal in dog food, at least in the UK.^[4]

There is some evidence though that higher standards for dog food were established in Europe in 2002.^[5] Additionally, the earliest source I can find for the question first being asked ('Where did the white dog poo go?') was in an online forum in 2006.^[6] Therefore we can probably judge that at least by the mid 2000's the chalky logs of old had crumbled for the final time.