Cats don’t only purr when they are happy. They also purr when they are in pain. It’s a way of soothing themselves. SO if you notice changes in her behavior even in the places where she is sleeping, take heed and make sure there isn’t a problem.
If you cat and dog has a lot of static in their fur, try using dryer sheets. Run one lightly over your pet’s coat to take out frizz and the friction. Don’t forget to wash your hands afterwards.