Abstract: Portable therapeutic devices and methods for employing them are provided by this invention. The devices include a flexible containment bag including a fluid chamber containing a fluid medium and a self-contained pumping means disposed within the device for causing the fluid medium to circulate within the fluid chamber to provide a therapeutic effect upon contacting the device with a patient. In preferred embodiments of this invention, integral electromagnetic transducer assemblies are employed to create a pumping action within serpentine fluid channels, and solid state heat pumps are employed to control the temperature of the fluid during therapy. The devices of this invention are ideal for treating lower back pain and post-operative conditions associated with spinal surgery, as well as veterinarian treatments.