Acupuncture is the stimulation of specific points on the body to elicit a biochemical and neurological reaction. The stimulation of these points can create a healing and balancing affect by the body. Typically, this response is achieved by the use of sterile needles inserted into these points. It has been used to treat animals in China for approximately 4,000 years, and has been applied in the United States for the past few decades. It is most commonly used in dogs and cats for the treatment of diseases such as arthritis, kidney disease, gastrointestinal disorders (in particular megacolon in cats), and some neurological, urinary, and dermatological diseases. The needles are usually left in for 10 to 20 minutes. During the initial treatment phase, it is common to have weekly sessions for the first 3 to 6 weeks. The frequency is then tapered off depending upon the response to treatment. For example, most older, arthritic dogs have maintenance acupuncture treatments every 2 to 6 weeks.