My cats also like to roll in the dust. I have learned recently though, that dirt is one way for internal parasites to find their way into your pets body. Mice and other rodents, and even some insects, carry parasites. The parasite eggs can drop into the dirt by way of feces. The cat rolls around in the dirt picking up these parasite eggs, then she grooms herself ingesting the eggs. I would suggest that if your pet is outside, and especially loves being in the dirt, that you keep her well guarded against internal parasite activity.