Interferential therapy is used to relieve discomfort in tissues experiencing pain. The current applied aims to invoke the body’s own pain defence systems, either through the pain gate mechanism or by stimulation of natural opioid release. The unit is usually set to sweep through a range of frequencies to ensure that the optimum treatment values are applied. The medium frequency current applied is comfortable to receive and horses respond to it well. It may be necessary to clip the hair coat of particularly woolly horses.