When you mix some children with access to markers and a black and white dog, this can happen:
If the markers were nontoxic, this is funny and kind of adorable. It makes me wish some dalmatians came with rainbow fur.
That being said, you should always monitor things like pens and markers around your dog. From a toxicity standpoint, most things (even sharpies) are nontoxic. Your dog might end up a bit sick, and if you are worried contacting a vet is best. Consuming too much can make them very sick. However, the most danger is when your dog chews up something like a pen or marker and then eats the plastic which can cause an obstruction.