How does it work?

There is no complete explanation for how it works but it can be partly explained by the "gate" theory of pain.
Endorphins are released while the needles are in place. These are natural painkillers related to morphine and this explains the drowsiness experienced by some patients.
However, a number of measurable physiological changes occur during needling and research into this is continuing.

How do I go about obtaining treatment?

Ask your veterinary surgeon to refer you. This normally involves no more than your vet faxing through a case history and you telephoning for an appointment.