There are many causes for eating sand and soil, one of them being a shortage of minerals. With natural food this is impossible (the mineral balance is optimal).
The two most frequent causes are:
1. Contrary to what many people think, pups do not know what’s good for them. This is partly inbred, the rest they learn from their parents and the other pack members and, for a considerable part, from experience, trying out things, e.g. eating soil. This behaviour does not only occur among young dogs, but among many young animals. Young horses or foals may do this as well, sometimes even resulting in their death. Arab thoroughbreds, for instance, are very sensitive to this.
2. Among adult animals the main cause is a form of boredom or letting off steam. Dogs that are properly fed and have a reasonable condition are extra sensitive to it. This also applies to pups and it’s only by anticipating their hunting urge (so, for sledge dogs pulling the cart or sledge) that the problem can be solved. For ordinary domestic dogs a brisk daily walk may already do the trick.