No, it is not considered dangerous for dogs to eat cat litter and its contents. This benign act is widely known as coprophagia throughout the veterinarian profession.
Though this is a highly undesirable act performed by many dogs, it is actually quite common according to the ASPCA. Coprophagia is commonly noticed in puppies and nursing mothers, but some dogs are known to carry out this act throughout their adulthood. While there is generally no cause for concern, some veterinarians may look at a few medical explanations, such as malnutrition and starvation.
Stopping the act of coprophagia can be a very challenging task. It is recommended to use deterrents such as Tabasco to eliminate the taste sought by dogs or odor eliminators to help keep animals away from litter boxes.