Dog stamps

The U.S. Postal Service recently released new stamps honouring working dogs.
The set of four stamps, that celebrates the partnership of dogs and people, depicts four typical jobs of working canines: guide dogs, therapy dogs, tracking dogs and search dogs.
The guide dog is a black Labrador Retriever, the sweet therapy dog -- pictured being petted -- is a Welsh Springer Spaniel. A yellow Labrador is the tracking dog while the search dog is a German Shepherd, standing in tall grass.